I will say that Avatar is probably the most visually stunning film ever done, and probably the most seamless use of computer generated imagery. The motion capture, effects, and overall look of the film are amazing. I will never debate that.
But I could literally see every plot point coming a mile away, and the reason for this is that we've all seen this same movie done before.
We keep jokingly calling it "dances with blue people". Spend the extra few bucks to see it on Imax or in 3D. If you can't do either of these, go to a theatre with DLP screens. It really makes the color pop.