My conclusion is that it makes pretty much no difference at all to me. As was generally the case with 3D movies i noticed the 3D effect for the first couple minutes, and then completely forgot about it. And for that first couple minutes my reaction was mainly "hey, you can see that thing X is in front of thing Y, and wow thing Y is really blurry." I presume thing Y was also blurry in the 2D version, but somehow the differential distance in the 3D version kept calling my attention to the things that were out of focus, at least until the point where i just stopped noticing the 3D.
I'm sure that at any point during the movie i could have intentionally focused on the 3D and started noticing it again, but i was too engrossed with actually watching the movie to think of doing that.
The one exception was right after she reached the ISS, there's a scene where several object fly directly at the camera, which made me flinch because of the 3D effect. However i don't really find that to be a desirable effect. And as soon as things stopped flying directly at my face i forgot about the 3D entirely again.
So i'm not bothered by 3D, i can see it just fine. It doesn't make me nauseas and it doesn't give me headaches. It seems entirely natural to me, in fact so natural that i just don't notice after a short period and it thus contributes absolutely nothing to the movie. I guess that makes me a rather small subset of the population or something.
Aside from the (lack of) impact of the 3D, there was one interesting thing about my second viewing of the film. It seems that the theatre we saw it in had a problem with its sound.
I first noticed it right after the first impact, when Sandra Bullock was spinning off on her own, and all of the sudden she started saying things as if she was responding to Kowalski, but we weren't hearing Kowalski saying anything. It wasn't clear in that context if she was hallucinating or hearing something we weren't hearing. Then when Kowalski got a little closer suddenly we could hear his voice. It seemed really odd to me because i had the impression that nothing like that happened the first time i saw the movie, but apparently a lot of the others thought it was some kind of artistic choice on the part of the producers or something.
Then when Sandra Bullock makes the shortwave radio contact with the guy on earth, you hear his voice loud and clear and they talk back and forth for a bit. Then when she sat back in the cockpit's chair the voice of the guy on earth disappeared, but she kept talking as if she could hear him. I _knew_ that nothing like that had happened the first time i saw the movie, and i formulated the theory that one of the surround-sound speakers was out, because that was the only thing i could think of to explain why the sound was sometimes there and sometimes not. Then when she leaned forward again, the camera rotated and all of the sudden the voice of the guy on earth came back, which provided pretty strong supporting evidence for my theory.
When the movie was over i mentioned the problem to the group and the one or two other people who'd also seen it before were like "yeah, i noticed that too" but everyone else was totally amazed. They'd all come up with theories (mainly the aforementioned "weird artistic choice") to explain the phenomenon, and were surprised to find out it was actually some kind of technical glitch.