The Godfather is undoubtedly the most acclaimed gangster film out there, but I'd take Once Upon a Time in America over it any day. In fact, I'd take Leone's film over any film full stop. It's just a beautiful film. It's a film about friendship, love, greed and time – all the good stuff.

One of the most audacious things in the film is the way the exposition is delivered. Noodles (De Niro) is in an opium den, high as a kite, and he's woken up by a buzzing in his head. But then as he looks at a newspaper with the faces of some dead gangsters on the cover, the buzzing turns into the sound of a telephone. And the telephone rings as we're taken back in time. The first thing we see are dead bodies on a street, one whose face is charred beyond recognition. Then we see a party, where Noodles excuses himself to make a call. But when he picks up the receiver the ringing telephone on the soundtrack doesn't cease. Then we cut to a police station and see another telephone. Only when this one is picked up does the telephone stop sounding. It's a very elegant way of showing Noodles' betraying his friends and communicating that he's in the opium den because his betrayal is ringing in his ears.

Just as elegant are the shifts in time. The film is wrapped around an elderly Noodles returning to New York after receiving a mysterious letter. He thought he'd escaped his mob life. But as he returns to his old home, we have extended flashbacks. And the transitions are beautiful. Indeed, one of them may even very well be my favourite bit in any film.

The moment in question is when the old Noodles returns to Fat Moe's more than thirty years after he left. Noodles looks at some old photos of his friends and then wanders to the back of the establishment. Morricone's gorgeous score swells and Noodles stands on the lid of a toilet. He then pulls a peephole back and edges closer towards the hole. Through the other side we see his sad eyes and when we cut back we see what he's seeing. We see a young girl dancing in the back room of a bar – Noodles' beloved Deborah. And then when we see Noodles again it's the young Noodles. It's an amazing piece of cinema, one that communicates the sense of loss we feel as we grow older and the blind excitement we feel in our youth.

And I do have to say that of all the sections in the film, I love the childhood scenes the most. There's just so much energy and life in these scenes. You have Noodles and his gang of degenerate friends burning down a newsstand, Noodles flashing his nymphomaniac neighbour, Patsy trying to buy a 'favour' from the aforementioned nymphomaniac by buying an expensive cake only to scoff it himself when he's made to wait on the stairs, and the scene where the urchins blackmail a policeman. These kids are little bastards, but somehow Leone infuses their scenes with such a degree of innocence. We love these kids. Therefore it's devastating when one of them, the smallest and perhaps most innocent, is shot down by a rival gangster. And when the child tells Noodles that he slipped just before he dies, it's heartbreaking. Finally the fun and games are over and the consequences of a criminal life are revealed.

One of the consequences is that Noodles goes to prison for avenging his friend's death and for stabbing a policeman. But when he comes out things have changed between him and his best friend Max (James Woods). They just aren't on the same page any more. Noodles would rather talk to Deborah than take an interest in the criminal empire Max has built up in his absence. But despite his lack of interest, Noodles does get involved. Indeed, during a robbery, Noodles is asked to put a cork in a woman who wont shut up. And he does so literally.

But this is a good example of a complexity in Noodles' character. He's an interesting mixture of a romantic and a thug. And an even better example of this is his reaction to Deborah leaving New York to go to Hollywood. This is the woman he loves, and he tries his best to woo her by taking her to a fancy restaurant and hiring it entirely for the two of them. But when she tells him that she's leaving, he's devastated. We see him in the car completely heartbroken. But Deborah makes the mistake of giving him a consolation kiss that leads to a brutal rape. Leone got into a lot of trouble for saying that this was an act of love, but he's right in a way. What Noodles does is completely wrong, but he does it out of a sick, twisted, obsessive love. In that moment he'd rather destroy her than let anyone else have her.

But it says something for Leone and De Niro that I care for this character. He does a lot of ugly things but he's human. And the scenes with the elderly Noodles are dripping with melancholy. "What have you been doing all these years?" "Been going to bed early," replies Noodles. Since New York his life has stopped. He's ceased to be a functioning human being. He's completely stuck in the past. And for some reason I always find it curiously moving when, early on in the film, when fleeing his hometown, Noodles asks for a bus ticket - "one way", he says. In that moment he might as well be putting a bullet in his head - he's ending his life.

However, although Noodles is forever stuck in the past, it's telling, in the scene where he's reunited with Deborah, that she doesn't appear to have aged while he looks decrepit. Are we seeing things through Noodles' eyes? Is this wishful thinking on his part? Whatever the answer, the scene is a marvellous one, one full of sadness and regret. In particular, I love Morricone's use of music and some of the lines. My favourite is something Deborah says: "We're both getting old. All we have left now are our memories." It's these memories that keep Noodles forever locked in the past. He can't escape the memory of seeing Deborah dance, or of her rape, or of his betrayal of his friends. Therefore he's stuck in limbo - maybe to lose those memories, to be put out of his misery, would be his only escape.

And it's quite interesting that the confrontation at the end of the film centres entirely around dialogue. The guns of Leone's westerns have been removed and in its place we have a more subtle duel. What I like the most is the way that Noodles refuses to acknowledge that this Senator Bailey, the person who raised him from the dead and brought him back to New York with his mysterious letter, is actually Max, the friend who he thought had died. His refusal to acknowledge his friend is another example of how stuck in the past he is. As far as he's concerned, his friend is dead and their friendship is, too - this man may as well be a spectre. Yes he knows it's Max, but as far as he's concerned, everything is over. Plus it's a subtle way of screwing his friend. By not acknowledging him by his real name and by ignoring his demands, he's maybe getting revenge for losing most of his life to his false grief - it's the only way that he can wield any power over this man.

And I find it audacious that a film that begins with a mystery - who brought Noodles back from the dead? - ends with another one. Does Senator Bailey/Max kill himself at the end? Does he walk into the trash compactor? And is it even Max at all, as we only see the man from a distance. Maybe Noodles is being fooled for a second time. Maybe this is another grand escape by his old friend. We never know.

And the film's final image is perfect. We see Noodles in the opium den. He smokes, lies on his back and the camera closes in on his face. For a few moments he's pensive, but then he cracks a huge grin. All his friends are dead (or so he thinks) and he's the one who betrayed them, but he's lost in oblivion. Finally, for a brief time, he's free from everything. And of course, this hints that the film could indeed be some sort of opium dream, but that's another matter entirely...

Directed by Sergio Leone
Written by Leonardo Benvenuti, Piero De Bernardi, Enrico Medioli, Franco Arcalli, Franco Ferrini and Sergio Leone
Produced by Arnon Milchan
Original Music by Ennio Morricone
Cinematography by Tonino Delli Colli
Starring Robert DeNiro, James Woods and Elizabeth McGovern.

Running Time: 229 mins

Rated R for strong violence, sexual content, language and some drug use.