Though this movie is not for children, it is a very real take on the super hero genre. Based on the comic book from the 80s of the same name, Watchmen is a tale of intrigue and supsense. Filled with deep complex characters, intact with flaws and differing ideals; the characters of Watchmen jump off both the page and the screen.
Many viewers simply didn't "get" the film...but I feel that was because many were expecting another "Emo Spider Man dance number" a-la Spider Man 3 or expecting something very family friendly. (Pay attention to movie ratings, that's what they're FOR!)
This is NOT a film meant for children. Heck, the COMIC is not meant for children. Both are gritty and realistic, sacrificing nothing and portraying solid and believable characters to the audience.
I know many fans complained about the slight change in the ending (the comic included some horrifying splicing of creatures that was vaguely reminiscent of a giant squid and the Cloverfield monster...it was the weakest part of the whole Graphic Novel in my opinion) but I feel that the ending that Zach Snyder chose to put in the film makes perfect sense and ties together well with Dr. Manhattan's lessening faith in humanity and his ultimate decision to leave Earth.
All in all, the movie is perfect, in my personal opinion. Strong actor performances (especially those of Jackie Earle Haley as Rorschach and Jeffery Dean Morgan as The Comedian) and classic choices in music that fit the era, all combine into a package that is well worth anyone looking for a different foray into the world of comic books.
If I had to compare it to any other comic book or comic book feel, I would have to compare it to Frank Miller's Sin City (though Watchmen came before Sin City). So if you liked that comic or film, you will more than likely love Watchmen. And even if you didn't, why not give the film a try? At least rent it to see if you'd enjoy purchasing it...the Director's Cut makes it all the more enjoyable an experience.