This film will never appeal to males who watch superhero movies just to gain vicarious pleasure from fantasizing that they are muscular men with great power. The main character, Kick-Ass, is a skinny nerd with no super powers or even martial arts training, and he gets upstaged by a little girl. He also gets stabbed in the gut and run over by a car whilst trying to be a costumed hero.
This movie is a satirical superhero story that really draws its inspiration from the ridiculous idea that Batman would bring a child (Robin) into the deadly, dangerous world of vigilantism, as well as the ridiculousness of being a costumed vigilante without any super powers. While Chris Nolan took the idea of a non-super-powered man in a silly costume playing vigilante and made some deadly-serious, utterly humorless movies out of that idea, this movie plays up the sheer absurdity of it all and revels in not taking it all seriously.
Matthew Vaughn invests soul into it and keeps the reel flowing as much as he can and there is a genuine plot in it too but unfortunately not enough reasons.