Playing updated versions of classic games is always something of a mind game: We don't remember the games as they actually looked so much as we remember them as our younger selves saw them. This can make it hard to judge just how much work has been done on the updated versions of these games, which is why seeing them next to the originals can be so instructive.
And I'll tell you what, the new version of The Legend of Zelda: Majora's Mask looks great, as this side-by-side comparison proves.
It's not exactly apples to apples, since the original game is being played on an emulator to making capturing the video a bit easier, and is shown at a higher resolution than the N64 release. That being said, the work done on the textures and lighting is far better than anything in the original N64 version of the game. This isn't even taking into account how cool the game looks on the improved 3D screen of the New 3DS XL.
So feast your eyes, my friends. The future is a cool place to live.