If you haven’t read the book yet, look away now…
I understand they had to change things. Film is a very different medium, and certain elements of the plot had to be excised for the sake of simplicity. There was no time for pirates, I see that. I think I would also agree that having a giant fake space alien teleport into New York might have stretched the bounds of modern audience credulity a little far. It was certainly simpler to blame everything on Dr. Manhattan than to explain the whole missing-artists-living-on-an-island subplot. I like the fact that they kept most of the bit-part characters, even if they had no dialogue. I honestly think they did the best they could with a tangle of possible storylines.
Visually stunning, obviously. Can’t fault that. And the music was pretty well chosen throughout, though personally I thought Hallelujah descended into farce. (There was some rather over-sentimental mood music, too, but that’s to be expected.)
What I would criticise is the charaterization. Given that so much backstory had to be cut out or glanced over, the acting needed to be really strong to make up for the lack of obvious motives. Veidt in particular seemed to lack presence, and Laurie was left with very little personality. I’m not saying the actors did badly: more that they weren’t quite given enough to work with. Rorschach, the Comedian and Dr. Manhattan, on the other hand, came out pretty well, largely because we saw more of their formative years.
These are minor complaints: it’s still one of the best graphic novel adaptations I’ve seen. Ultimately, I think we have to accept that a book and a film will always be very different things. There is, happily, room for both.