It's probably his best movie so far, but also the most extreme. I see you're 14... this one really pushes the rated R limits in some scenes.
For what? Violence? We Americans don't think anything of violence. You can put as much of it as you like in film, and half the time it will remain PG-13. We just don't like any of that filthy sex. Any of that, it gets an immediate R rating. Anything crazy, it's labelled porn.
I think it's funny that several movies in the US are rated R for a sex scene, but in Europe they are equivalent to PG-13. Our cultures seem to be opposite. I've read of American movies getting banned for graphic violence. Personally, I wish people thought of violence as being worse. One of them is showing people kill each other, and the other is just babymaking. Yes, lets shield our eyes from the one that is natural and not a bad thing. Makes sense....