This movie doesn't try to be anything it's not. It's all about kicking ass! The unsuspecting hero was in fact not Kick-Ass himself, but Hit Girl: an 11-year-old girl with katanas and a potty mouth. Every fight scene with her was pure entertainment. Go see this movie, if you're not a wuss.
Hands down the best movie I have ever seen. Most movies you walk out of the theater going "It was good, but...". Not with Avatar. I can't think of a single bad thing to say about this movie.