Disclaimer: I work for a company that makes 3D film making equipment and I'm a bad marketing person because I'm not really fan either. That said, there's a HUGE difference between films that are actually shot with actual Left-Eye/Right-Eye camera rigs and those that are shot in 2D and retroactively made 3D. Part of it us just the post-production that fails, but I find most of the problem is in the cinematography. When the director/photographer is thinking about each shot in 3D they'll set them up differently. However, most Hollywood directors think a good 3D shot just objects flying towards the screen.
The only 3D movie that I think fully used the capabilities of the medium was Werner Herzog's
Cave of Forgotten Dreams. You wouldn't think that a documentary about paleolithic cave paintings would be the best application of the technology, but it was amazing. The surfaces of the cave are so dynamic and the way the artists used the curves and textures of the cave walls to imbue the drawings with depth and motion is just incredible. That's something you're just not going to see if you have a flat view.
I think 3D has applications, but on the whole, it's not being done right. Especially the post-processed films - the
only reason those are being turned into 3D is so the studios can make more money by jacking up ticket prices. If there's a legitimate story-telling or artistic reason to shoot a film in 3D, and you've got a cinematographer who knows what they're doing, it can be done well. But that's such a small percentage.