I don't really like the use of 3D even when the film in question was designed for it in the first place. Indeed, if given the option, I'll always choose a 2D showing of a film. For one, it's cheaper; going to the cinema is expensive enough as it is, so to spend another £2+ for the 'privilege' of putting glasses on top of my own is not an experience I wish to have. As well as this, even without accounting for any wild and wacky effects, I really don't like how much darker the screen becomes as a result of the 3D technology. The last film I saw in 3D was Toy Story 3, but I had the advantage of seeing that in 2D beforehand, and the drop in image quality was just astounding. It was that experience that put me off 3D, for the most part.
There are, of course, exceptions. The best use of 3D that I've seen has to be Pina, a German documentary film about experimental dance choreographer Pina Bausch. It's only in this film that I've seen 3D used to truly immerse the audience in the film, and it makes the breathtaking dance sequences come alive in a way that you do actually feel like you're watching them on a stage, instead of in front of a screen.
But that's the exception that sort of proves the rule in many ways. I'm very pessimistic when it comes to 3D technology, preferring stuff like IMAX for the 'immersive experience' portrayed by the film-makers who choose/are forced to use it.