First of all, I think that this was an amazing piece of cinema- Absolutely beautiful to look at. Now, I've never read the book yet, so I can't compare the two, but as a film alone, I'd say that this was fantastic.
The violence, I found, was actually rather low (though, coming off of Priest, which is a VERY violent movie that I watched only a few hours earlier, I can't really say that I could judge well as I took it in). The CSM review covers it, really, and I don't think I could say what hasn't already been said in that department. I think some of the images would be a bit disturbing to some, but I wasn't really unsettled.
There were a few kisses, and I kinda got the idea that the murderer was a pedophile (o-o), but over all, it's nothing most people my age haven't seen before.
Mild language. One use of "f**k", a few insults. I've heard worse.
Grandma smoked and drank in front of her grandchildren. In every shot she had, she was holding AT LEAST one cigarette.
Sends a good message that one shouldn't go off alone with strange people, no matter if they seem harmless or not, and that things like this could happen to anyone.