Lots of cool effects and a couple of hot girls make it worth seeing. It has a lot of dumb humor that only high school kids will enjoy and a silly plot, but these movies aren't made to win academy awards.
The movie tries to strike a balance between a "turn off your brain" action show and a drama with constant plot twists. Unfortunately, it doesn't really accomplish either very well.
There are times when it does feel fresh and unique. I thought the music and visuals for the opening credits were very original, but then it ruins the dark feel by throwing in cheesy cliches throughout that remind me of the Joel Schumacher Batman movies.
It's not something I would watch more than once, but it is worth seeing for the Rorschach character, which is the highlight of the movie.