I have heard that it's amazing. Of course, it was based off of a graphic novel, so that automatically makes it cooler. Then again, Hollywood changed it considerably. For example, in the novel the main character is pretty evil (once he walked into a police station and KILLED EVERYONE just because he could) and characters like Fox (Angelina Jolie) are only minor characters, not as major as they are in the movie.
KIDS: Don't think that flinging your pistol as you shoot will curve the bullet. It won't. You're twice as likely to hit some random, innocent passerby. You CANNOT do the things in the movie, no matter how cool you are. It. Defies. Physics.
That being said, enjoy the movie!