Finally got to see it. Great fun.
Cessna - I was cringing at the "noble savage" take to, and was seriously debating whether I wanted to put myself through it. Then I was told "The Secret" to keep in mind while watching the film... not only takes the edge off the Rousseauean wet dream push of the film, but also shuts up the "whats with the different body plans and non-mammalian heroine with boobies" sciency voice in the back of your mind...
... the Na'vi are gen-modded human colonists who designed their own body plan and
built Eywa generations ago. No, it's not canon at all and JC would prolly freak to see his message so distorted.
But it explains -
* why an alien species with a completely different body plan from the rest of the local fauna can still "link" with other animals and the hometree network.
* why said alien species has human facial features, gestures, expressions, culture... and boobies.
* why despite their low tech they don't seem to be experiencing the problems real-life stone age tribes have had.. recurring famine, constant intertribal warfare, disease.... the ecosystem was - and continues to be - managed by the biological-based AI their ancestors created as a caretaker.
Plus, if you really have a bone to pick, just pretend the RSA-folk from earth are coming from such a retarted tech level compared to the biotech required for all that above 'cause of the effect of [insert whatever political system you don't like, but don't say what it is here].