Now, walking into a film called Kick-Ass you expect some extreme action, and or violence. Beheadings, shotgun blasts to the face, etc. But when Kick-Ass and Big Daddy end up in a bad way, that is really unpleasant to watch, it becomes too much. If you watched No Country for Old Men and thought, "Why is this Anton Chigurh guy such a choir boy? He should act with some malice!" then this scene with head mobster Frank D'Amico (Mark Strong) might be your cup of tea. Anyone else, however, will probably be disgusted.
But there are two things going for it: Chloe Moritz and Nicolas Cage. Hit-Girl is an interesting take on why a sidekick becomes a sidekick, but ultimately it's just funny to watch a twelve year old girl kick the asses of low-life thugs. Nicolas Cage looks like he's finally found some career resurgence with this and the Bad Lieutenant reimagining, hopefully this career transition manages to last past Sorcerer's Apprentice and Season of the Witch. Cage, an avid comic-book aficionado got his chance to play a decent superhero - no, I'm not counting Ghost Rider.
I didn't hate this film (violence against children aside), but it just doesn't seem to have that spark that most comic book films have. If you want a subversive film that skews the conventions of a comic-book film rent Defendor instead.