The graphics, detail, textures, character models are all infinitely better.
It's obviously overlayed over the original game itself, though, so the animations are the same. For instance, in the video, when Link gets hit by the boulder it does that HEAD EXPLODED thing over his head and then he walks through it just like in OoT.
That's not a problem because the animations were pretty solid in OoT. Not the best, but when you think of OoT it's certainly not the animations.