Errr... Just 3D slide is rarely use & my 2DS is collected dust.

I don't use it. There's no point, in my opinion.

Worse framerate/graphics, reduced battery life, has to be angled perfectly. All that just so certain parts of the image look farther away.

I play my 3DS the most out of any of my modern consoles atm and i rarely turn the 3D on. I may use it more on the "New" 3DS or least try to.

rarely, because i use my 3ds while laying back on couch and sometimes it does not work well. and it drain a hell of batteries.

Yes! It looks pretty great on games like Smash and ALBW.

I would if it didn't give me an instant migraine headache. I mean that literally. It takes about 5 minutes and I'm down for the day.

Most of the time, yes. However, for some games, keeping the slider at the top is just too much.

Pilotwings Resort is an example of that. Ugghh.

Always, it's just better.

With 3D on, I'm better at aiming shells in Mario Kart or better at jumping platforms correctly for example. It also makes the gameworld feel more alive. In Luigi's Mansion 2, it looks like each room is a diarama you're looking into. Or a puppet house, it's really cool. In A Link Between Worlds, everything looks soo deep. In fact, you must play that game with 3D on, because you'll miss half the game if you don't!

I've just bought a new 3DS and have been trying the 3d. It still doesn't seem to hugely work

Part of the problem is wearing glasses and often playing without glasses on. It doesn't quite make it work properly. It works better with my contacts, but I still don't see the benefit

Overall, I'd rather avoid the potential for headaches and help boost my battery life

Depends on if I'm tired or not.
I usually don't though, I fiddle around a lot when I play (especially while on handhelds).