As far as the story goes, well, we've probably encountered it before more than once. It's not District 9.
But the SFX? Wow! Pandora is probably the most beautiful alien planet we've ever seen. Dangerous, yes, but lush and glorious, with believable creatures designed by Wayne Barlowe. (Well, believable if you bend the square cube law a bit, and given alien physiology leading to carbon fibre permeated bones, and an atmospheric composition comprising goodness knows what, flying creatures able to carry 10' aliens manage to carry it off.)
And those tall aliens? They're this side of the uncanny valley. They manage to be strange and yet not repellent, despite their blue skins, noses that are more like muzzles, and their inhuman height.
In total, this film will be earning back Cameron his investment, and it's going to be providing the technical tools for the next generation of SF films. I'd love to see this technology used to film C J Cherryh's Atevi.