I've now had a chance to finally read Watchmen and see the movie twice. There isn't much to say, really. I enjoyed both the comic and movie thoroughly. The comic is classic Alan Moore, and the movie possibly the best superhero movie made to date (even with the changes to the ending, which, luckily, were fairly well written and, just possibly, even more plausible than the original, though some of the dialogue near the end could perhaps have been trimmed).
Though I love the genre, there are rather few real masterpieces in it, with the possible exception of a couple of the Batman movies. (I haven't actually seen The Dark Knight yet, I must confess.) But of course the same can be said for any adaptations of stories to new media. And basically all (serious) superhero movies are adaptations of comic book characters, aren't they?