The visuals were amazing - especially in IMAX 3D (at least when my eyes, which are rather hit-or-miss with 3D, were working properly) - but beyond that...
It really didn't have a lot going for it besides the visuals and was weighed down by a cliche-ridden plot.
As I put it to Scott afterwards, apparently James Cameron decided to take everything he's ever seen, read, or heard and put it all into a movie.
But, to be fair, I wasn't really expecting much more than amazing visuals, so I can't exactly call it a failure, and I was entertained by it.
It just would have been nice if, along with the trailblazing visuals, Cameron had opted to tread some new ground with the story as well.
(The story: white man goes to live amongst savages, white man falls in love with the chief's daughter, white man learns the ways of the savages, white man turns against his own people - who, naturally, are eeeeeevvvvillllll, because guess what: sometimes "civilized" people are the most savage of all! Irony! - to protect the way of life of the savages.)
It's definitely worth seeing, but don't get your hopes up in thinking that, underneath the flashy surface, you'll actually be seeing anything new.