We bought a new TV for the Olympics that happened to have 3D - it wasn't a selling point we were interested in, but it was the best screen we could get for the money (Samsung UE40EH6030 - £430 from Argos!).
So we watched the opening ceremony in 3D just to see what it was like, and it was really, really good. Not only did it look fantastic - the rings coming together and the cauldron were genuinely amazing spectacles - we also had better commentary by the sounds of it. We've watched some of the other 3D events on Eurosport and the daily round up on the Beeb: they're OK, but not outstanding. The swimming looks good, especially the underwater bits. I suppose the opening ceremony was better planned than the day-to-day stuff.
I'm not 100% convinced, but I'm much more enthusiastic about 3D than I was before. My wee girl _loves_ it - seems to be totally convinced by the illusion, keeps ducking out of the way and trying to catch things .