Oh My God SEE THIS!
I went to see this wonderful movie with a friend, who's also almost 12, and her little sister, who's almost 8. It's now one of my new favorite movies. It's not filmed by a genius like Peter Jackson or anything, but the camerawork is quite good. At the beginning, the actors were so good that I thought it was a documentary - I would have never known that this was actual acting, it looked so real. The story is great and there are some hilarious moments, although younger kids might not get them (a soldier calls his girlfriend, the girlfriend hears a woman's voice and thinks he's cheating on her). It's well done and makes you think. My only complaint is the subtitles - I'm a really fast reader, but sometimes you miss stuff.
There is some language in this, but it's used completely in context and makes sense. It's not anything that kids over 9 (or kids who have older siblings and were taught curse words) wouldn't have seen or heard, so that's all good. I'd say it's good for 8 and up, and it wouldn't hurt if smaller kids saw it, although they probably wouldn't be able to read the subtitles fast enough.