Watchmen is a referential adaptation of its source material. As such, it boasts the same strengths and suffers from the same weaknesses. The strengths are its imagination and the way it perverts the superhero genre, and the weaknesses are the disappointing final act and the episodic nature of the narrative – the story doesn’t really flow.

Thankfully, though, the movie, by necessity, has pared the story down. In the graphic novel there are large sections that feel pretty superfluous. Yes some of the digressions helped to give the story colour, but at other times they threatened to derail the whole enterprise. So I, for one, think that a little focus has helped things a lot.

One of the sections that was less than enthralling in the graphic novel was Dr Manhattan’s exile to Mars. On and on it went and it soon grew tiresome. But weirdly enough, in the film, it’s one of the highlights. It manages to convey Manhattan’s isolation and alienation without bashing it over your head.

My favourite part of the Dr Manhattan thread is the flashback sequence that gives you his back-story. We see him fall in love and then we see his rebirth. It’s very economically done and it accurately captures the stream of conscious nature of memories. We don’t see things in chronological order. We see little pieces of the jigsaw puzzle.

The sequence is also ripe with melancholy. As the sole superhero in the world, he’s gifted with unparalleled powers. However, these powers detach him further and further from humanity. He can no longer relate to the ordinary person’s petty concerns. As such, as he looks back on his life, his voice has the passionless hum of Hal from 2001: A Space Odyssey.

But despite this, Dr Manhattan is not devoid of emotion. In one scene he’s coerced into appearing on a TV talk show and is then confronted with a former lover that he apparently gave cancer to. His anger and his distress is so intense that he exiles himself to Mars.

However, even though I enjoyed the Dr Manhattan story, you can’t escape some of its juvenility. This is a man who cries for people to leave him alone and who basically goes to his room to brood when life gets tough. And this juvenility extends to the character of Rorschach, the masked vigilante who spouts fascistic voiceover like a second rate Travis Bickle.

But even though the character is derivative, Rorschach does get all the best action scenes. And mainly for that reason he ends up being perhaps the film’s most enjoyable character.

One of the best bits of action is when Rorschach fights a bunch of cops. He takes an improvised flamethrower to them and then manages to fight off half a dozen of them with his fists alone. I also enjoyed the way that Rorschach takes out a prison inmate – he throws burning oil over him. And then there’s the grisly way that he disposes of a child murderer – he repeatedly pounds a meat cleaver into his head. All of this stuff superbly captures the grime of the character.

Other action sequences don’t fare as well. Some of the fight sequences, especially the ones involving Nite Owl and Silk Spectre, are far too fanciful. For instance, there’s a jailbreak scene where Nite Owl and Silk Spectre fight off a dozen or so inmates. They don’t have weapons. They don’t have gadgets. All they have are their fists. And so it doesn’t really ring true that this supposedly out of shape man and this less than threatening woman could beat up a bunch of grizzled convicts so easily. The action in this scene is just done to try and look cool.

Another action scene that doesn’t really work is the final battle between Ozymadias, Nite Owl and Rorschach. People bounce off walls and punches seem to have little impact. Consequently it all feels a little pointless.

And the film, like the graphic novel, suffers in the final act. The first problem is that Ozymadias is a colourless villain. He doesn’t have any menace and he isn’t any fun. Secondly, the twist of him being the bad guy is revealed far too late. Instead of feeling like an inevitable plot development, it feels like a desperate way of giving the film a resolution. Yes the film gives a few hints that he might be a bad guy, but his character is so far on the periphery that it’s hard to summon any enthusiasm when his true nature is revealed.

One big improvement in the final sequence, though, is the attack on New York. In the graphic novel people are killed by a giant alien squid thing. However, in the film there’s none of that nonsense. A ball of energy just wipes everyone out.

But although the ending is less than stellar, there’s still plenty to enjoy in the film. In particular I enjoyed everything to do with The Comedian. He’s a terrible person, far worse than the tedious Ozymadias, but he has some of the most memorable scenes. One scene that springs to mind is his attempted rape of a fellow masked hero. It’s vile and it’s brutal but it also makes for riveting cinema. The Comedian is such a sick perversion of the traditional American hero that you can’t help but wish that the film was dedicated entirely to him.

I also love some of the small moments in the film. There’s a dream sequence where Nite Owl and Silk Spectre rip off their skins to reveal their true nature underneath – underneath are their superhero costumes. Somehow these alter egos better represent their true selves. And this fact is further illustrated by the way that Nite Owl fails to perform sexually when he’s in his civilian clothes. He can only perform when he’s in costume.

And the kinky relationship between sex and heroism feels honest enough – Nite Owl and Silk Specter seem to perform their heroic acts largely because it makes them hot. That I can believe in and enjoy a lot more than a knob who thinks he’s Alexander the Great killing lots of people with a ball of energy so that he can save even more from the fires of nuclear war.