I have seen Avatar and it is a good film, not great though. I do think that it is quite overhyped. The story for me is a bit predictable and that does take away something from the film, in my honest opinion. But then again, that is from a personal point of view and I anticipate that there are people who will disagree.
I agree with lamp_abi. I don't understand why people can't stop raving about it. It's too predictable for me. The effects were great but the story was okay.