I've just finished playing The Legend of Zelda: Ocarina of Time 3D. OOT is my favorite Zelda game, and I played OOT on both Nintendo 64 and GameCube, I know the game inside and out. In two days (almost) non-stop, I finished the normal version with all the Piece-of-Heart, 100 Golden Skulltula, 4 bottles and all the weapons. Simply 100%.
3D effects were sometimes a little too strong for me, but since it is possible to set the degree of 3D, this was no problem. If you also have played a few other 3DS games before, your eyes have become accustomed to it.
Apart from the obvious 3D effects, there were some other changes from the original. This version was much easier, even for the new players.
If you’re stuck and don’t know what to do, you can visit one of two special Sheikah-stones that will give you very revealing clues. I tested this once to see how it worked. Good for those who are lost.
The Water Temple has received a "nerf". Very obvious visual clues show you where to go. Nevertheless, I managed to miss a Small Key.
I was disappointed in the boss fight against Ganon. He was much smaller and not nearly as scary. Almost every boss that has a "weak-spot" has had it marked with some kind of luminous texture.
The bridge to Ganon's Castle has a different design.
The owl talks less, but still has Yes/No options in the wrong order.
Navi is as annoying as we remember her. Now she even tells you to save and take a break.
Sheik’s new movement patterns and model changes give in general hints for a more feminine body. Sheik has a slightly different way of showing the true identity, compared to the original.
It is difficult to roll forward to avoid injury after a fall; the analog stick is very sensitive. You can aim with either the analog stick or by moving the entire 3DS. This gave a new level to the boss fight in the Forest Temple. Otherwise it was very easy to get good accuracy.
All of Hyrule has received a major facelift with new textures, improved models and better looking animations.
I do not know when it was unlocked (I discovered it shortly after I got Master Sword); if you as young go to sleep in your bed then you can do Boss Challenges where you meet the bosses you've already killed. I have not tried this yet.
Those of you who played the old Ocarina of Time may remember the Super Mario-portraits that can be seen through two windows in Hyrule Castle, before you talk to Zelda. They are no longer there, but there's something else there. Try to shoot it with the slingshot.
When you defeated Ganon for the first time, you unlock the Master Quest. It will apparently be the same Master Quest which was in the GameCube, though all enemies hit twice as hard and the whole Hyrule is mirrored. I have not tried this yet.