Well, I saw the movie on Wednesday, and feel that Ebert was taking it a bit too seriously. It's made quite obvious that the film-makers realise that Hit Girl is effectively a child soldier, and they play this up throughout for both uncomfortable laughs and occasional drama. For instance, there's a very good reason that her father never gives her the 'if you kill them, they are really dead' talk - namely, that he's a deranged ex-cop with an unhealthy fixation on comic-books who's been moulding her into a living weapon for most of her life. How effective the movie's attempts at deconstructing superheroes are is a matter of debate, given that they are evenly mixed with a certain sense of fun and spectacle that slightly undermines them, but I didn't find that the conflict detracted nearly as much from the movie's entertainment value as in, say, Inglourious Basterds.
As for how faithful the movie is to the comic... well, I must confess that I haven't read the latter, but from what I've managed to glean about it from the Internet, it's safe to say that there are changes. However, this is not necessarily a bad thing. In my experience, there are two types of story when you're dealing with anything other than straight-up black-and-white morality - the kind where there is a genuine affection for the cast, often regardless of alignment, and the kind where the entire thing seems to be saying to you "Hey, look at these losers. Don't they suck? Let me show you how much they suck." The latter greatly irritates me, and is one of the reasons that I couldn't stand Closer. It is also the category into which, by all accounts, the Kick-Ass comic falls.
The movie, meanwhile, allows a measure of humanity in its characters' portrayals, and a measure of optimism in their lives. The geeky protagonist gets over his vigilante fantasies. Hit Girl gets a shot at a normal-ish life. Big Daddy is shown to have had lines even he wouldn't cross where his daughter's training was concerned. Even Red Mist, the main villain's spoiled supervillain-wannabe son, gets a couple of humanising moments here and there. The changes may rob the story of some of its deconstructive edge, but they're quite welcome nonetheless.
See it yourselves. Make up your own minds. It's been said before, but it bears repeating.
