This movie was absolutely beautiful -- visually and emotionally. Although I'm sure it is a great movie in "normal" 2D, I can't imagine not seeing it in 3D. The lush scenery and amazing living things on Pandora truly astound you watching them in 3D and the battle scenes are incredibly vivid.
Beyond the stunning graphic effects, the movie has amazing messages about interconnectedness, war, and nature to impart and does it without making you feel like you're being lectured to.