I saw it yesterday, oblivious to the fact that it was the anniversary of the sinking (not uneducated, just had my days wrong.) I have to say, I thought it was a phenomenal movie already but the 3D was so subtle and unobtrusive that I understand Cameron's passion for it. Also, I had never watched the movie in a single sitting before but thought that the pacing of the story was surprisingly well done for a movie of such length.
All of that said, we saw the Prometheus trailer in 3D before the movie started...the entire time I was wondering how a Cameron-level quality, post conversion of Blade Runner would look...