Na'vi side of the game was ok, but playing as a human was terribad. Also, ran into a game-breaking glitch at the end of the human campaign. Wasn't worth the one gold trophy to start it over. Collision detection on vehicles is some of the worst I've seen. Overall, a perfectly subpa game based on a movie, but if you're a huge fan, stick with the Na'vi side of things.
This really is a stunning game with vibrant colors, unique concepts, and a decent story line. It's very surreal and you can loose yourself within the game but then the monotony sets in and even though you're presented with new items and new scenery, the objectives are still the same: run here, ask him, run there, kill them, run back and ask him, run back and kill them again..... it gets really old especially when you have to bounce back and fourth several times to complete an objective. I was very relieved to finish the game.
Avatar allows you to chose sides which might have been to improve the game's replayability. Regretfully this was not the case but it's a good concept. It's a "rent" if you like the movie but certainly not worth buying.