Avatar is a great achievement on many levels, but not perfect by any means. I thoroughly enjoyed the graphics and special effects. It was visually awesome.
Flaws include: (1) 3D is not a high-value improvement. I would not pay extra to see it. This film would have been just as good without it. The glasses are a pain. (2) editing was flawed, several times the size of the Nuvi relative to humans changed inexplicably, (3) the painting of the military and the amoral corporate despoiler was heavy handed. You could argue that a lot of people who see the movie wouldn't get it if it were subtler and that may be right. (4) the script was often stupid and childish when depicting the military types. Didn't add to it.