Mike is sincere! Also, I thoroughly enjoyed Kick-Ass. I was worried when I saw Mark Millar's name in the opening credits, because I didn't like what he did with The Authority and I despise Wanted. However, he can use violence effectively in service to a story (not as the point in itself). A feat accomplished here also. However, this is an adult, mature-themes movie (and I'm not talking about sex) and is not for children.
I think Kick-Ass works much like the original Scream does. It is both a critique and a functioning example of the genre.