3D, IMHO is a gimmick..
However, one issue I don't know if has been raised yet... 3D requires HDMi v1.4.. (as opposed to HDMi 1.3x, which is probably the most common standard)...
Not sure what the implications of this are yet
I've considered it to be a gimmick since it's recent resurrection but I had a go of Motorstorm 3D at the weekend while visiting my wife's friend on their new 3D TV and I was surprisingly impressed. It gave both depth to the track and was quite effective at throwing debris out of the screen. There was a little bit of double imaging on some objects although no worse than Avatar at the cinema, tbh I still think it's a gimmick although I am more open to it now but would only buy into it if it could be done without the glasses.
HDMI 1.4 will probably be an issue for a lot of people. As well as getting the new 3D TV they had to get a new AV amp as their existing one didn't support 1.4...they also got a new separate Sony 3D blu-ray player so save waiting for the PS3 update! Perhaps more money than sense but it was an awesome set up.