I saw it this weekend and generally liked it. Definitely a far more faithful adaptation, for better or worse, than I would have ever expected could come about.

I'd say that in presenting the cliff's notes version of the story the most notable loss were all the characters that weren't superheroes... All of the man on the street stuff has been dropped. Cops, the news vendor and kid, the editor of the paper, most of the psychiatrist, etc. If it didn't directly involve one of the "Watchmen" (as the movie named them), then the scene was dropped. Understandable, but then it does make the big attack at the end fairly hollow without knowing anyone caught in it.

All told though, I liked it. I do think that, for someone who hasn't read the comic, it would be much like the Harry Potter movies are to me: There's a fair amount of interesting stuff, but the overall story of each movie itself isn't particularly great, and I just figure that there was a lot more on the page that make the stories worth telling... the details that suck one into the adventure and make it such a treat.