"Avatar" is an engaging, visually-stunning movie in the classic James Cameron style.
In truth, the story is familiar ground, and comparisons to "Dances With Wolves" and "Ferngully" are not without merit. However, a good story is always worth retelling, and this one is told well. I'm not usually one to get emotional during a movie, but I freely admit I got choked up several times during "Avatar."
Some people have accused "Avatar" of pushing some left-wing liberal agenda with its anti-imperialism themes & "treehugger" message, but if this movie makes people think a little more about the path humanity is on, then that can only be a good thing IMO.