Watched it. In 2D, as I'm tired of the 3D overkill, so I'm done with that. Avatar, on Imax 3D, is still the torch bearer for how to do a 3D movie.
Gravity is fantastic. A bit of stretchiness in technical, but it's just so well done, you can get past that. Story's simple, but it's important for it to BE simple. It's about the difficulties, not a story about the characters per se, except what would they do to survive.
I'm thinking of going again.. and yes, even the 3D version this time, it was that sorta good. I don't see movies twice much, this one I might.