Rotten Tomatoes ratings are 77% by reviewers and 92% by audiences. That's a very big thumbs-up overall.
I try to enjoy movies rather than be an arch critic. I watched it on Tuesday in 3D with my daughter and my wife. The enjoyment I extracted was around the native environment, the social interactions, and the spiritual connection between the various animal life forms and their planet (which the story analogises biologically with the 'melding of nerve ends'). The plot was full of holes. The fight scenes were the usual childish fare for American action movies. The narrative was utterly unexceptional, but not off-putting. I came out saying "there was enough to enjoy, but I'm not going back".
The choice of 3D was my daughter's: I haven't watched in 3D since disliking it 10 years ago. So this was going to be an interesting revisit: would I like it now?
Well, I must say, I thought the third dimension itself was tastefully done and very effective. I enjoyed it. BUT. Just like 10 years ago, every time I slipped the glasses down to see what I'm missing (and ignoring the 'double-vision effect of not using the glasses'), I thought wooooooowwwwww, look at the glorious brilliance, contrast and dynamic range to the image. And OOOOOOOOMMMMMMMMMGGGGGGGG, the colours! Vivid, glorious, saturated, accurate (to the 2D edition), such an enormous jump in visual pleasure.
Put the glasses back on.... all gone. But hey, it's 3D now. To me the 3D is worth having and adds (say) 20% to the visual experience, but not at that cost, which subtracts 50% IMO.
Imagine if the option of stereo sound for music, instead of mono, was made available, but only by wearing cheap industrial earplugs, and not allowed to increase the loudness to compensate. All the dynamics and impact gone. All the frequency response accuracy gone. But hey, that stereo effect is quite nice. Would you take the stereo option on those terms?
cheers