I read it when I was 14.
But I refuse to watch the movie for two reasons:
1.) Its directed by the same guy who directed "300." And I wouldn't be surprised if the guy just glazed with the same gaudy and ostentatious slow-motion effects and make the audience completely forget what the original comic book was trying to say.
2.) As a genuine fan of comics, I will refuse to watch the movie out of resepct to the source material's writer. I'm not exactly sure how many people know this, but Alan Moore was apocalyptically enraged when his baby was going to get the Hollywood treatment, and he's on my short list of top graphic novel writers (others include Pat Mills, Jean Van Hamme, Pierre Christin, Alejandro Jodorowsky, and Garth Ennis. Read the stuff written by these guys, you'll be blown away).