@Marcsman: motorstorm 3d rift
@Sin4profit: that's exactly right. I felt I was focusing on things in the map a lot more and trying to process too much. The HUD, messages that pop-up, and the sights of guns are very distracting in 3D - because it either pops out or looks further away. The RDS in black ops 1 was totally messed up in 3D, the red dot was like further away from the sight itself, so it made it harder to aim.
And yes, I feel that in a slower paced game the 3D would add a sense of immersion without getting in the way like it does in fast-paced games.