It's really not. Honestly, the adaptation of "Wanted" was MUCH more violent than this movie. I almost opted out of going to this film, despite my love for comics and my enjoyment of Mark Millar's work. I'm glad I went. Seriously, the worst thing about this movie is probably the one above-adult swear a 10 year girl says - and that really means nothing once she starts cutting up bad guys.
And even the big time violent, stabbing, beatings, and gun shots - it's never drawn out unless germane to the plot, and even then the plot-line is quick enough to not let you dwell on the overly horrible things that happen in this movie. An example of what I'm trying to explain: when Hit Girl (the 10 year old assassin) cuts up a bunch of gangsters, many limbs are cut off. These wounds are barely seen after the initial cut, and aren't even overly bloody.
The real reason this movie, I think, got such a harsh response from critics, is because it involves a 10 year old girl doing bad things. I heard a lot worse than appeared in the recent movie Runaways.
Yes - 10 year olds should not be assassins. Yet this movie was clearly never advocating such a thing, and the concept was executed with more humor than anything else.
This movie was simply a laugh riot. Every poignant swear and overt assault often left the audience laughing. This was a funny, well thought out and smartly constructed movie. Just the pure concept, of an idiot deciding to really become a super-hero, is so seamlessly executed, that this movie can stand as the definitive take on the subject.
Although I'm a comic fan, and a Mark Millar fan, I didn't actually read the comic this movie was based after. I was told, even by the creators themselves, that the book was too violent. Whatever the comic was actually like - the movie adaptation seemed perfect.
Mind you, I'm giving this movie a lot of praise - but it is, indeed, violent. But never so violent or outrageous that I was ever offended or disgusted. (And, to be honest, I can be very squeamish with truly violent movies. I steer clear of Japanese Gore films, for example.)
The overly protective media and watchdog groups are simply overreacting to this film. It's indeed not for kids - but no where near as bad as Roger Ebert would have you believe.