I actually thought PS3 3D was great, but few games utilized it well and in most it just tanked the FPS (I remember Redboxing Black Ops 1 for the 3D and it was a disaster). Super Stardust HD in 3D is fucking awesome though. I wish more people could have seen it.
The 3DS 3D was also kinda nice. There were a couple games from early in its life where it really did make a huge difference (OoT 3D and 3D Land). But then as time went on it seemed to matter less.
Overall it's a gimmick but it's a nice one to have. I think the issue is that it only really matters if the game is designed with it in mind, and that's not going to happen when it limits the audience that can enjoy the game. And if a game isn't designed with it in mind it often leads to performance being worse for a nonsignificant benefit.
For movies I thought it was mostly good, especially if it was filmed with 3D in mind. Avatar, TRON, and Hugo are all awesome 3D movies (and Journey to the Center of the Earth is.....uh, not that great of a movie but has some really cool 3D effects). Even if a movie isn't in 3D I don't mind it but it eventually started seeming like a waste of money when there wasn't really a tangible benefit.