What I'm about to say may constitute comic-book heresy, but Watchmen the movie is better than Watchmen the book. The director has managed to pick the best, most exciting parts of the graphic novel and edited out the boring stuff (Tales of the Black Freighter, anyone?). And whereas the art in the Watchmen comic always struck me as too sterile, the movie's visuals are stylish, emotional, and even set to music.
If you've never read the comic, it's set in an alternate reality where there were a couple of superhero teams: the Minutemen (1950s), and their successors the Watchmen (1970s). Both teams eventually disbanded, due to political pressure. This alternate history is depicted in the gorgeous opening montage (set to Dylan's Times They Are A-Changin'). The story focuses on the living members of the Watchmen, one of whom has recently been murdered. It takes place around 1985, but there are a lot of flashbacks, so keep that in mind while you're watching.
Rumor has it that Alan Moore, creator of Watchmen, took his name off the movie halfway through production over creative differences. I'm not sure what his problem was, seeing as the film is remarkably loyal to the comic. Most scenes are so similar that I'd swear they used the graphic novel as storyboards. The performances are excellent, especially Jackie Earle Haley (Rorschach) and Jeffrey Dean Morgan (the Comedian). Watchmen is a long book, with a lot of little stories and big ideas. Turning it into a film is no easy task. Yet they managed it without diminishing the individual characters or bungling the plot. Alan Moore set out to blow up comic book cliches and raise questions about human nature, and the movie stays true to that. Looking at the final product, I think he'd be proud.
Beats the hell out of V for Vendetta, anyways.