One thing I don't want is 3D for 3D's sake. You know, the scene where the rock/knife/car/plane/bullet/etc. is shown coming right at the audience in slow motion so that the audience can really get a feel for the 3D-ness. I fear that a large majority of the movies released in 3D will have these tacky tricks going on throughout the movie so people can be wowed and impressed with the new set that the industry has just made them buy to replace the 2 year old set they just got for HD viewing.
That said, I haven't seen a 3D movie since Captain EO at Disney Land many, many years back. If they just make good movies that also have 3D that is in no way obtrusive into the movie, I wouldn't have an issue with it.
Personally, I'm not all that interested in replacing my screen, PJ and player for 3D (not to mention the need to buy what will likely be expensive glasses for each seat.)