So, let me be honest. I've played through Ocarina of Time, like, 10 times. Between the original release, Master Quest, and Virtual Console, I really didn't see a lot of reason to rebuy it for Nintendo's latest handheld, even with the upgraded graphics. I was actually pretty shocked to find how different the game felt on the 3DS, and it's not a purely aesthetic change.
Of course, the visuals are the most advertised change, and they certainly are gorgeous. We're not talking about the original Ocarina of Time with 3D added. The textures are incredibly rich, and very clearly individually redone, rather than just artificially enhanced. The climeable vines, for example, now look like real vines. Link's individual fingers are visual, and all animations, motions, and framerate seem signifficantly improved from the previous ports. Of course, the 3D itself adds a great effect as well, providing great depth to the environments, and a lot of added immersion and realism. The map actually sits on the foreground, while the environment spreads out in front of you in a perfect example of effective use of 3D depth. Even the little sparkles coming off of Navi float around in the foreground in a realistic and effective manner.
There are certainly some gameplay changes as well, though. Two items can be assigned to X and Y on the 3DS, which are activated in the same way they were on the C buttons on the old 64. More items, however, can be assigned to the touch scren, and are easily activated with the simple push of a thumb, thanks to the 3DS's significantly improved touch screen sensitivity. When using items which require aiming, you can either use the slide pad as you would on the Nintendo 64, or you can use the motion sensors to quickly aim and turn the handheld. This works very well, although with the small 3D deadzone you'll need to turn with the device.
I played through the first part of the Kokiri Village (got my sword and shield) and then entered the Great Deku Tree and spent another 5 minutes screwing around in there. The game plays great, as you'd expect. Targeting is done with L, movement with the Slide Pad, sword attacks with B, and a jump attack and roll with A. Other than that, well, it's Ocarina of Time, and that makes it awesome. Prettier, smoother, and in 3D. Why wouldn't you want this? You can expect Ocarina of Time 3D sometime before June of this year, but unfortunately, not at launch.