Before I saw Avatar, I thought the whole "3D" movie thing was just a headache inducing gimmick. This movie proved to me, that in the right hands, it is a very effective medium. The immersion within the environment is miles above anything I've experienced with normal video.I think the reason that the story has taken a back seat is just because the visuals just stole the entire movie. (Think Joker in TDK). I regret seeing it on a smaller screen theater now and find myself wishing I'd seen it on IMAX. Do yourself a favor and just see it on IMAX instead.
Possible Spoiler, so highlight as you please.
Firstly, this story has been done many times before so the plot is nothing too special. My biggest problem with the story was that the humans were presented as nothing but greedy one-dimensional beings with nothing but wealth on their minds. I felt that more could have been done about the story of the colonel instead of him just being a hardass the entire time. I also thought more could have been done to show why they needed the unobtanium so much, other than "its worth a lot of money". Maybe it could have been the cure for a plague that is wiping out human kind. Cameron never gave us a reason to side with the humans.