Man, I have to say it's indicative of the film that the thread had slipped to page 2 already!
So much less that I was hoping for, not that I know what I wanted but you know what I mean - I guess I was expected pacing, excitement, emotional involvement as well as kickass CGI.
<spoilers>
Instead we get an overly-long (it's actually boring in places) effects showcase where the effects actually aren't really that good and the central characters on the native side are sooo anthropomorphic it's just ridiculous, but on top of that they're supposed to be a clan and yet somehow the main characters are idiosyncratic enough that they don't seem to be closely related - you can tell they're voiced by specific racial types and, oddly, in some cases modelled differently to match. It just doesn't ring true.
Aesthetically I didn't care for the native tongue, just didn't grab me, in stark contrast to the proto-Egyptian in Stargate for example; even Klingon is better, despite being built up ad-hoc to a degree. It really sounds like Cameron might have designed it himself, without recourse to a linguist. Add that to the Smurf-blue skin and the sub-par animation (most of the dinos in Jurassic Park are honestly more convincing than the Na'vi) and I just couldn't connect for almost the entire film.
The CGI is wide in scope (the bulk of the movie is computer-generated) and much of the planet looks amazing, the vegetation in particular is a knockout, but as we're used to in CGI the technological stuff looks best although I didn't take to the design of much of the military hardware. It seemed a bit old-school and not that special considering we're talking in an era of interstellar travel.
Honourable mentions: Stephen Lang, um, acting circa The Hard Way? And as good as Worthington is at covering it, just like in T4 his Australian accent peeks through in places, particularly when he's shouting.
</spoilers>
But maybe it'll grow on me...
Einion