2D. Definitely seeing it in 2D.
The problem was that it was too dark. One of the most common criticisms of the current crop of 3D movies is that the glasses you have to wear noticeably dims the film. At best, this can be an annoyance, but if you've seen any of the footage of Tron Legacy, you know that the computer world within the film is already pretty dark as it is.
Dark skies. Dark costumes. Dark walls. And anything that isn't dark is a dim shade of blue or orange. So, for two minutes, all I could see were shapes moving about.
Oddly enough, the result looked like the cover for the Art of Tron Legacy book.
It wasn't just the dimness that made it look bad. All the smoke effects and lens flares didn't translate all that well into 3D, and most of the time the 3D effect wasn't even that noticeable.
So, yes I'll be in the theater opening weekend to see it, but in good ol' fashioned 2D.
Art of Tron: Legacy image is copyright of it's respective owner and used under fair use.