A visual feast, Avatar suffers from a story line we've seen before, and an indulgence in SFX that pads the film by 15-20 minutes. The 3D was a delight, character development and portrayals were strong, and Avatar was fun to watch. But I did glance at my watch a couple of times (not a good sign), and I kept hoping (in vain, as it turned out) for an unexpected plot twist.
The 3D ought to put a lot of butts in seats, and the film deserves its accolades for use of SFX. The sci-fi is entertaining (Orson Scott Card came to mind as I watched Cameron's film), but nothing new. And the same essential story is featured in many films (e.g., "Dances with Wolves" & "Local Hero").