It's a really good feature that works well, but I don't use it that often (only really in cutscenes): 8/10

I don't like it personally.

You mean in Zelda, the Chamber where the sages inhabit? Not doubting you, but I don't remember seeing anything weird, I think.

Another negative thing about the 3D is that it completely negates gyro controls - not that I like them that much, but still.

Damn, I got a glitchy 3DS? :(

As for the gyro, the thing is that you're supposed to move not only the system, but also yourself so that the 3D won't be affected, which of course makes you look like a dumbass

9/10, the only issue is being able to only have that sweet point with a larger angle view, appart of that sometimes is better than in some cinemas

I still prefer to play in 2D tought.

A generous 8/10. That's when ignoring the narrow viewing angle.

I won't play 3DS games without the 3D slider at max, but still divide play time with DS games in 2D.

As already pointed out, the narrow view angle doesn't mesh well at all with gyro based controls because no one instinctively tilts their head/eyes in the same orientation as their hands. Watching people drive would be hilarious if such were the case. But that's a pretty minor gripe.

Any game that tends to cause movement of the 3DS in general is less than optimal on a parallax barrier display.

The narrow view angle is probably the weakest aspect; I'd almost rather wear polarized lens glasses for any angle 3D, just not on a handheld.

To make you feel a little better, maybe you could have glitchy eyes! :P

3D is always on. I've not played a game yet where I preferred flat 2D.

8/10 from me. It works well on Zelda but I don't really use it on Zelda. It's hard to concentrate in dungeons so I'm forced to turn the 3D off. It's hard using gyro controls with 3D on however and sometimes I see double images but that is rare.

I won't throw a number at it. I'll just say that I always play with the 3D turned up to the max. That "sweet spot" is an issue, though. Too often, I'll be playing a game and I'll really be into it and I'll move the system and suddenly everything goes to shit. It's easy enough to get it back to normal, though.

There are times where I can play the same game and the same level and the 3D will look better in one environment and worse in another. I guess it's a lighting thing. I also found that the 3D pops out more if I look at it from a slightly lower angle instead of directly head-on. Either way, it's a great feature and I love it.