I went to see Avatar in 3D last night with Scotty. I liked it a lot, though the 3D made my eyes hurt a few times (mostly when something was close to the camera but not actually in focus, or when there was a lot of action).
I did have trouble hearing the dialogue in quite a few parts. It's one of the ones I will have to get on DVD just for the subtitles. Made me wish they had 3D subtitling here!
It was strange - normally I can tell a difference when the volume increases for the actual movie after the previews are finished, but there didn't seem to be an increase this time. The most difficulty I had was at the beginning - trying to get used to both the 3D and the voices of the actors as they sped through some of the exposition was difficult. I was actually grateful when they slipped into the foreign language, because I didn't have to "work" so hard to understand what was going on both visually and acoustically.
I'm still glad I saw it in the theaters though. It's definitely worth it for the big screen and the 3D!