It would be an understatement to say that Lars von Trier polarises audiences. It seems that half the people think he’s a genius, while the other half think he’s a talentless idiot.

I certainly belong to the former but Melancholia is a first for me - I experienced both ends of the von Trier spectrum in one movie. The first half is an appalling, crappy, half-baked mess while the second half is a powerhouse.

The first half details the wedding reception for newlyweds Justine (Kirsten Dunst) and Michael (Alexander Skarsgard). The first time we see them, they’re in the back of a limo as the driver tries to navigate a narrow country road. He has difficulties trying to get his car round a particularly tight corner.

I immediately took a dislike to the couple. They make snide comments about the driver and then when they finally go to help him, it seems like they’re trying to have fun at his expense - both of them have a go at trying to get the car round the tight corner but it seems like Justine has never driven before; she can only giggle when she smashes the front of the car into a cinder block (at one point the driver begs them not to damage the vehicle).

They arrive a couple of hours late to their reception. Given these circumstances, you’d think the newlyweds would be apologetic and compliant. Instead they immediately run off to goof about in the stables. They behave like children.

The friends and family of these nitwits aren’t much better. Justine’s mother (Charlotte Rampling) is a contender for the most miserable person on the planet, Justine’s father (John Hurt) is the resident ‘comedian’ who thinks that it’s a great idea to fuck around with the waiting staff, Justine’s boss (Stellan Skarsgard) is a selfish prick who doesn’t attempt to hide the fact that he’s only interested in Justine for her ability to make money, Justine’s sister (Charlotte Gainsbourg) is dull and gloomy and Justine’s brother-in-law (Kiefer Sutherland) is a wealthy jackass. There’s a very high concentration of pricks.

The opening hour ends up serving as an anti-Deer Hunter. In Cimino’s film, the wedding reception helps us to identify with the characters and to form an attachment to them, so that when they’re exposed to the horrors of war, the pain is almost unbearable. In Melancholia, the reception seems to distance us from them.

It’s made clear that Justine is a troubled woman but her relationship with her new husband is so hollow and facile that it almost beggars belief. At one point he gives her a photo of an apple orchard - apparently he’s bought the land in the hope that they’ll grow old together there. But when Justine is called away from the room, she leaves the photo behind. So much for happily ever after.

But as thoughtless and uncaring as this is from Justine, her husband doesn’t really deserve any sympathy. At the end of the evening he tries consummate the marriage, but he’s about as smooth as a crocodile and Justine brushes him away. The man has all the charm and class of a sewer rat.

The film’s nadir occurs when Justine leaves her husband to gloomily wander her brother-in-law’s golf course. Following her is one of her boss’s lackeys. Rather than tell the guy to piss off, Justine pushes him to the ground and fucks him. The staging is horrible. Apparently the kid gets an erection in about two seconds and then we see Justine bouncing on top of him - it looks like she’s riding his stomach.

But of course the scene doesn’t work on a deeper level either. I get that Justine is supposed to possess a depressive personality. And I know that manic depressives are prone to wild mood swings and engage in self-destructive behaviour, but the acting and the writing just aren’t good enough. Justine just jumps from Point A to Point B to Point C without adequately communicating the inner turmoil that is leading her to behave like this.

There was one point in Melancholia when I was ready to completely write it off. After getting fucked by Justine, the lackey tells her that they should go into business together, saying that, after all, they’ve had ‘good sex’. [insert sound of a cosmic forehead slap ringing across the galaxy]

Thank fuck then that I have an almost pathological inability to abandon a film, because the second half is amazing.

The planet Melancholia is heading towards Earth. The official story is that it’ll just pass by. However, other people say that it’s going to smash right into the Earth and destroy everything.

The second half begins with a severely depressed Justine staying with her sister Claire at her enormous mansion. Justine can barely move and finds even the simplest everyday functions impossible - she can’t even raise her legs to get in the bath. Obviously distraught, Claire does her best to raise Justine’s spirits. In one scene she cooks her sister her favourite dish - meatloaf. At first Justine seems to enjoy it but then she begins sobbing, saying that the meal tastes like ashes.

Her marriage in ruins and her life a complete mess, it seems like Justine has already experienced her own private apocalypse. It’s only when a much bigger disaster begins to loom that she rouses from her slumber and returns to something like herself. When she’s already lost everything, what is there to fear?

Indeed, it seems that Justine openly welcomes the end of life on Earth. Like she’s suddenly become Werner Herzog or something, she proclaims that all life on Earth is evil and it deserves to die. And then when Melancholia does its fly-by of Earth, she welcomes it like a siren - in the un-Earthly glow of the rogue planet, she bathes nude in the river. Perhaps Melancholia is a welcome release from her terrestrial problems.

Claire’s husband John doesn’t believe that Melancholia presents any danger. He and his son watch the planet get closer and the fly-by is a cause for celebration. His son even invents a contraption that helps track the rogue planet. With a stick and a loop of wire, he’s able to see if Melancholia is getting smaller or bigger. As predicted, after the fly-by, Melancholia begins to move away. It seems like everyone is safe.

In the morning, though, there’s an eerie quiet. Claire goes to the stables and sees that the horses are completely still and calm. She then finds her husband’s body - he’s killed himself with an overdose. Claire rushes back to the terrace of her mansion, picks up her son’s invention and sees that Melancholia has come back and is closer to the Earth than it was before.

Claire’s reaction to the impending disaster is sheer panic. She has a son, a good home and a comfortable life, and she doesn’t want to lose these things. Justine on the other hand is icily calm. She even mocks Claire’s idea of having a farewell party with drink and music - the end of the world is imminent and you want to have wine and music; how bourgeois!

Justine realises that hysteria won’t accomplish anything and makes sure that her nephew experiences the least amount of trauma possible. She says that she’s going to make him a magic cave out of sticks and that it’ll protect them. After so much selfishness and self-absorption, she finally achieves a state of grace with this act of decency and kindness.

It’s quite amazing how tense the final half of the film is, especially as we already know the ending - the prologue gives it away. The spectre of death looms over everyone and the inevitability of their demise is crushing. We get to see all of their hopes dashed, we get to see them panic and struggle and flail around like insects avoiding a boot that wants to stomp them - it’s a psychologically stressful film, especially if you have a family; you’ll do anything to protect them but what if you’re completely powerless?

It’s also a fantastic decision to have such a small focus. At one point I wondered how the rest of the world was reacting, but what does it matter? We’ve already seen mass hysteria in disaster films - it’s never particularly interesting. But here we get to see a small group of people dissolve right before our eyes. They’re literally crushed by forces beyond their control, which reminds us of how precarious our own lives are. We have far less control than we think.

The only thing that keeps this film from greatness is the abysmal first half. von Trier doesn’t have to pander to his audience but some measure of likeability in his characters would have given it a bigger jolt at the end. Or not even likeability - I just need a better understanding of the characters and their actions. A better actor than Dunst would have been welcome too. Although I do have to say that she improves greatly in the second half.

But you can’t help but feel that von Trier is happy that these people are being destroyed. This is great if you’re into schadenfreude, but not so great if you want a deeper emotional resonance.

What makes Alien such an effective horror film is how quiet it is. After all, most horror films make the mistake of equating fear with noise. But that's often a mistake, as silence is usually infinitely more effective. And so it is with Alien. The scariest moments are all devoid of intrusive scoring, jagged editing and overblown sound effects.

One of the best examples is when Brett is killed. He has to chase after Jones (the cat) and he's led into a dark corner of the ship. You know he's going to get killed but Ridley Scott knows that you know. Therefore the sequence is dragged out. All the time you're waiting. You're waiting for the inevitable. But Scott doesn't rush things. He racks up the tension by having Brett wander for an inordinate length of time and by having him wash his face in a shower of dripping water as chains rattle in the background. And when the Alien does appear, it's not with a sudden jolt. It just appears quietly behind Brett before killing him. And the way that the death is played on the face of the cat, which has a look of almost stunned curiosity, makes the whole sequence incredibly spooky. It's not really a crash, bang, wallop sort of horror film.

Not that there aren't any jump moments. There are actually quite a few. But because the lead-up is so quiet and ominous it makes the pay-off a whole lot more effective. For example, when Kane looks into the egg. Again the sequence takes its time, racking up the tension to breaking point with the discovery of the ship and the slow exploration of it, but when he finally has a peek and the facehugger leaps out, it has the perfect timing of a great joke.

Another fantastic piece of timing is when the Alien takes Dallas. You go through another long, drawn out sequence of him scurrying through narrow air vents before the Alien finally pops out of a dark corner. But although the moment is fantastically timed, the lead up is where the fun lies. And I have to say that the lead up is probably the most frightening thing in the film. Dallas scurries through narrow corridors searching for the Alien, but you know it's futile - we know that he won't find it and that it will find him and that it'll kill him. And the dark, claustrophobic corridors are full of iris-shaped doors that open and close slowly and forebodingly, which really does add to the air of dread that fills the sequence. And the tracker is the icing on the cake – it racks up the tension to breaking point.

The second most frightening sequence is when Ripley is finally alone in the ship. She sets the Nostromo to self-destruct so that she can take the shuttle but then with strobe lights flashing all around her she sees the Alien. She then goes back and tries to reverse the self-destruct sequence, but it's too late. It's frightening because Ripley has to run around the ship, not knowing where the Alien might be. No longer does she have the option of just hiding. And with everyone dead she no longer has anyone to talk to or help her out. She's all alone. But perversely, once everyone's dead, the film finally gets loud. There's a countdown sequence (which is brilliant in the way that it raises the stakes - not only does she have to face a terrifying monster, but she's against the clock now as well) and the ship begins to destruct. Just when Ripley might have needed the silence to find out where the Alien is, she has to run around in cacophony of noise knowing that the Alien could be anywhere.

But the silence comes back in the final sequence, and it's quite ingenious the way that the Alien is camouflaged in the shuttle. I nearly shat myself when I first saw it as a kid.

What I also like about the final sequence is that it's weirdly sexual. Ripley strips down to her underwear and then the Alien appears. And the Alien then begins almost stroking the console it's resting on. And of course, Ripley penetrates the Alien with a harpoon.

Another excellent bit of weird sexuality is when Ash the robot tries to choke Ripley with a magazine. He shoves it in her mouth and he looks rather turned on as she gags on it. Perhaps robots don't come with all the parts. Perhaps this is his way of venting his frustration. But there's also the way that the Alien kills Lambert. Its tail inches up the insides of her thigh and then you cut away and hear her screaming like she's being violated – the screaming is actually pretty chilling. And of course, Kane getting ripped open goes back to the male fear of childbirth. (The birth scene is still great. The blood, the sound and the way it takes the Alien two or three attempts to burst through is fantastic. But I do have to say that the way the Alien shoots off the table looks rather dodgy.)

Going back to the Lambert killing, though... As well as being chilling, this scene is also quite frustrating because Parker (Yaphet Kotto) gets killed as well. I mean, Parker is quite possibly the coolest man in the universe. I swear he could have taken the Alien had it not been for the cowardly Lambert. (It's quite surprising that the coward and the black character survive so long – they're usually the first two to go.)

But although I dig Parker, I think Ian Holm as Ash delivers the film's best performance. It's quite subtle the way that he hints at his true identity – I like the way he jogs on the spot to get his joints working. And he's so smug and slimy. He's more of a villain than the Alien.

But I think everything in the film is fantastic – the music, the special effects, the sequence on the alien planet, the production design, the moody atmosphere, the script. Everything works perfectly.