This movie is fantastic but........the plot completely lacks imagination. It's Apocolypse Now, Aliens, Jumangi, Star Wars and a Disney movie all rolled into one. You've seen this movie before--just not all in one place.
That said, there were times I couldn't tell if the Avatar was a person in makeup or CG--that's how good this movie's special effects are.
Go see it--you won't be disappointed but don't expect some earth-shattering plot.