Related question How often is it that the 3d is used in game play, I seem to remember some game using it to help show hidden items etc...

For the curious I have no real depth perception due to a childhood ailment so no 3d tech is going to work in any real way for me.

I never play with 3d on. And have never had a problem playing a game. But now that you say it I do think super Mario 3d world dose do something like that. But if you have nit tried the 3d out on the 3ds you should. It isn't exactly likevthe glasses. Although it dose use the same premise.

I have it does not work with my condition its basically like having one eye closed constantly nothing will ever work for me. heck the real world doesn't work for me cant get a drivers licence.

Very few games do you need the 3D, The only one I have played where it is ideal... not really needed is Mario 3D land. I do also think that the 3D effect kinda smoothes out the visuals on some games.

Just like @Dagbiker, I very rarely play with the 3D on, and when I do, it's just for a few minutes to amuse myself with the novelty, not because it's needed. It can be avoided even in some games that use the 3D feature as a gameplay mechanic (some puzzles in Super Mario 3D Land, for example). But, really, you won't be missing anything if you can't use the feature.

I almost always have it off; it's usually an annoyance more than a useful feaure.

I would say do not let the 3d weigh into you decision on buying the machine at all, for me i turn it on for about 2 mins after i get a new game just to see how it looks then turn it off, the only exception to that would be mario 3d land of which I think is the only 3ds game to look really good in 3d but it still looks really good without it.

The games look fine without 3D, and most games dont even need them. So you will be fine