I love 3D - I have it at home and on a 10ft screen viewed from 10ft away, 3D feels much larger than 2D does - I suppose, it’s because when watching 2D, the brain realizes that the screen is still quite tiny compared to a real cinema but in 3D, the comparative distance is not so easy to discern.
Also, the image quality looks better to me in 3D - I would appreciate 4K in my projector when watching 2D, because I can still see the individual pixels but I can’t see them at all when watching a movie in 3D - I suppose it’s because the brain is getting twice as much picture information in 3D. I never had a problem with headaches or anything.
Actually, the 3D setup I have at home is better than in both local multiplexes - it produces nice, bright image and has no ghosting whatsoever, which is a problem I always had in the cinema, so now I don’t really go see 3D movies in cinema, see the 2D version and if it looks like it would be good 3D, I buy the 3D Blu-Ray, which is why I’m quite terrified by the news of BD3D losing support.

As for DVD, sure, for some movies, it is perfectly serviceable, if you’re watching on some tiny screen, but HD will still look better, which will then make the entire experience better.