Does the 3DS version of Ocarina of Time have more or less content than the original Nintendo 64 version?
Compared to the N64 original, a little over double. The reason for this being the inclusion of the Master Quest, which was not originally available on the N64 version. Although it was released later as part of a special promotion. The world is mirrored in the 3DS version of Master Quest, but everything else is the same as the previously released version.
The only content which is 100% new is the boss challenge mode.
According to Wikipedia, the 3DS version includes the original game (in 3D) and also includes the Master Quest (which is a harder version of the game). It also allows you to use the touchscreen to equip items, and the built in gyroscope to aim items when in first person mode.
There's also the Sheikah Stone Hints (like in the newly released Skyward Sword).
You get to order your C-items any way you want in your inventory.
The Master Quest is harder since you take double damage. And some minor things have been changed as well (some chest locations in dungeons).
Fishing seems to be a bit harder than in the original version.
And of course 'enhanced graphics' is a major understatement since they added a LOT of stuff mostly to the houses - people no longer have crappy homes, they have wardrobes, cuttlery, paintings, and there's many posters on the wall in Kakariko Village (outside), etc. So I would say there's more extra content than you would think.