Absolutely.

It adds a subtle yet amazing touch to the games.

I usually keep it off if I'm really into a game or are focusing like Monster Hunter or Smash but I still do use it commonly.

Never, always have it turned off.

I always try to but if I start noticing the 3D (like if it takes me out of the game with ghosting or the bad view angle), I turn it down until it isn't a problem. One of the reasons I want a New 3DS is because I love the 3D effect but I wish I could use it more..

Barely..

If there is a cutscene or still image, I may turn it on for a bit to see the 3D effect but will turn it off soon after.

The 3D makes me dizzy especially for games like Mario Kart and it drains battery faster (want to game longer!).
I also have to position and keep my head in the sweetspot. Even if get the n3DS, I probably won't use it much.

I would say it depends on the game...
But lately I really haven't been using it at all...

Sometimes, just to see how nice the game looks if its turned on, I'm not sure, but it kinda removes some jaggies if I turn it on, but that's just me.

Always. I actually like the little 3-D effects enough to where the 3DS seems a little bare without them.

It was about 30% on the old 3DS, but about 100% with the new.

Depends on the game. Majora's Mask, Ocarina of Tme, Fire Emblem Awakening, or Bravely Default? Yes. If not, probably not.