The best way to describe it for someone who is trying to make up their minds is this: "Avatar" mixes the best parts of "Dances With Wolves", "Last of the Mohicans", and "Aliens", stirs them in with great storytelling, stunning setting, and incredible movie making techniques.
I was spellbound.
There were predictable parts, but they were predictably Cameron. I could definitely see U.S. Colonial Marines fighting Aliens on another planet and the Corporation is still there and acts in its own interests ... like a "sequel" to that sad universe that Mr. Cameron created 30 years ago. But, this time Ripley gets to come home.