The 3DS's style 3D-effect is definitely underrated. I don't care much for 3D in movies (mainly because of the glasses), but for games it's certainly useful. It really does make games look better and especially play (a lot) easier. In fact, because of the effect and the helpful added depth, I'm slowly getting worse at jumping correctly in a 3D-plain in 'regular' games on my 2D television. And also, I agree about the posting of 2D images on Miiverse... Just turn on that 3D people!
Anyway, most games's 3D effects are pretty good. I was quite impressed by Ocarina of Time but now almost three years later it's clear the tech improved. Besides Super Mario 3D Land which proved the usefulness of the effect gameplay-wise, to me the most noteworthy games are:
Luigi's Mansion 2: Each room it's like looking into a diorama, greatly improves the game's graphics. I played the demo of Castlevania and it gave me a similar feel.
The Legend of Zelda: A Link Between Worlds: The depth effect is amazing (Death Mountain Crater looks like it's a mile deep), it helps in solving puzzles and in getting a better feel of the layout of an area.
Mario Kart 7: It's so smooth I've never had that game's 3D effect 'ghost' on me, it also helps greatly at judging distances and angles to other karts so you can more properly aim your projectiles.







