What I don't understand is why people take their kids to see films like that. It was pretty explicit in places (it's rated R) and one family took their 5 or 6 year old to see it. I'm sorry, but if you can't find a sitter, you don't take your kid to see that film. It's rated R for a reason folks.
Incidentally, I know that R means you can take a child so long as you go along too, but to my eyes, just because you could, doesn't mean you should as far as I'm concerned. Kids are exposed to enough stuff that forces them to grow up quickly, and don't need any extra help as far as I'm concerned.
Oh by the way, I'm a little surprised that one particular group didn't complain about the film. I won't give the group's "area of experience" away (it'd give the film's twist in the tail away), but that shouldn't stop them from complaining.