We purchased a 3D TV since it was just slightly more costly than the non-3D model and it came with 2 pairs of active shutter glasses for free. In the year that we have had it, we have only watched two movies in 3D, mostly because Netflix and Redbox only have the 2D versions.
Gaming has been the primary use of the 3D technology for us - Uncharted 3, Wipeout HD, Killzone 3, Resistance 3, The Sly Collection, Hustle Kings, and just last night I tried the remastered Jak & Daxter HD Collection. I think gaming is where 3D shows the most promise; you could almost say it adds another dimension to the experience ;)