I also like that the storyline deals with consequences. Everything that happens has far-reaching, unexpected consequences. Sometimes it’s little, like Todd off-handedly mentioning that the person arrested as Kick-Ass is actually his father, a revelation that leads directly to the elder Lizewski being brutally murdered; or Brooke not realizing that the person she’s built up in order to tear down and torment to make herself feel good is trained in warfare. Sometimes it’s much bigger, like everything the Motherfucker does is due to Kick-Ass killing his father in the previous film. Hell, both movies are a consequence of Lizewski’s decision to become Kick-Ass.
But the biggest one of all is the massacre outside Night Bitch’s house, when Mother Russia starts mowing down cops. At that point, all bets are off, and everything changes, because cops have been killed, and they crack down.