Avatar has, in my opinion, WAY too much strong language. I just don't understand why a movie like this "needs" all that. It wasn't nasty, just a lot of exclamations. A tad violent, but not really bloody per se. Also, you might want to be aware that the alien people are very human-like and the females are pretty topless. If they were human, I beleve it would be counted as nudity without a doubt. They're covered, but only with necklaces and such.
All that said, it was one of the most amazing 3D movies I've ever seen, I enjoyed it very much, and I'll probably see it again in the theater! It was stunning! The 3D was very believable and didn't give me a headache. If you and your family can cope with the elements described above, I strongly recommend seeing it. In 3D for sure.
If not for the language, I would have rated 5 stars.