I played the original on the N64 years ago, loved it. This remake is near perfect. It's evident that the graphics could have been improved to make full use of the 3DS's graphics capabilities, but I don't think that would be true to the original art style of the game. The graphics look amazing as they are. The touchscreen design works fairly well, except for having to tap the screen to access some menus/options which you can't access via buttons (because of the lack of buttons of the 3DS compared to the N64 controller). The gyroscope makes aiming tools a breeze.
Other than that, it all works. It's a full adventure game; sidequests, secrets, you name it. This will keep you occupied for a while, especially if you're new to the game. Plus, it has the bonus Master Quest version after you beat it, which basically is an updated version with modified (harder) dungeon layouts, maps and settings, so essentially, it's an entirely new experience.
This is a solid game, and should be in every 3DS owners' collection. A remake of Ocarina of Time, regarded by many as the best game ever made, was always going to do well. Ocarina of Time 3D is no exception.