I've been reading pieces of the ongoing discussion since the first screening, including among many (much more in friends only or less public blogs and journals):
I finally saw it yesterday; it definitely has some issues with race and White guilt. And there were some science and strategy glitches that made it really hard for me to suspend my disbelief at times. Ie: why the hell would the "Colonel" rig the shuttle with bombs when he had Missiles? and other idiotic behavior. And the Corp? they wouldn't really pull out after one defeat would they?
So there are most assuredly race issues, but there are also other issues (in particular ableism and sexism) that Cameron handles poorly at best. Jake in a wheelchair made him a bit less offensive to me as part of the "white guy saves the native cliche" because he is a minority and treated as such quite often in the film by his fellow humans. It also felt like he fell in love with the physicality of his new body and his alternate life as a Na'vi as he learned their ways, trained in the skills he needed to become Na'vi, and finally fell in love with Neytiri.
And then there's the sexism toward Grace & Trudy (and why aren't there more human women in the film?), Grace's attitudes toward Jake at first (as if to be intelligent you have to have college degrees), the anti-science stance of both the Corp and the Colonel, etc.
The humans' attitudes toward Jake as a man lessened some of the racist discomfort in a way (not that racism and ablism are the same, but they both create limitations whether visible or not, and they both change the way the majority acts toward people), and the fact that in joining the Na'vi Jake threw away his chance at walking again as a human also made his character less problematic for me. He did wind up as a fully able bodied Na'vi, but that was after he'd disobeyed orders, watched his few human friends die, and saved for lack of a better word the Na'vi Mother Tree.
I was also kind-of glad to see Cameron's clear statements on Corporate greed, protecting the environment, and pseudo-military operations here. I silently cheered when Neytiri shot the Colonel in the chest twice; not only was he wrong, he was doing bad things for pay. The Blackwater and other NGO parallels were obvious in a good way.
Overall, I'd give the movie at 3/10 for it's handling of minorities, a 6/10 for treatment of human women, and a 9/10 for the 3D and CGI. I would like to see a directors cut sans 3D at some point - I think there's more to the Jake/Neytiri relationship than we get even at 2 hours 40 mins long. After all it was nearly 3 months of training with the Na'vi compressed into an hour at most of screentime.