One reason why "Kick-Ass" is getting a ton of buzz is due to the character of Hit-Girl. Played by Chloe Moretz, she is 11 years old, she cusses, she kills people.
This red band (red band!) trailer from IGN may show why she is a candidate for breakout actress/character of 2010. Much of the action images were seen at the "Kick-Ass'" Comic Con pane,l but it doesn't matter: There are still some doozies here.