Actually, a lot of the art assets from Advent Children would barely be usable. Since none of them could viably be run in an engine (nevermind that the characters themselves are completely different models to that movie) due to tri-count, and reducing tris is a huge task in itself for something so complex as that tech demo that they'd be better off going from scratch.
Looks good to me. It stays very close to the original art direction, so I'm not sure what you're getting at. Unless of course you hated the art direction from the original game.