1st and FOREMOST, MUST HAVE ADULT LINK.
No jellybean with a tunic style graphics, give me a fluid more rugged look that the fairly dark series deserves.
Make link a bit WORLDS manlier, give me some cutscenes of him flying off a bridge, grabbing the ledge with one hand, etc etc, showcase some adventure spirit and make link a non-pansy prease.
Make the story... interesting...
Bring back the awesome area's the series is trademarked with :P I want a forest maze, I want a mountain path with falling rocks, the dark rooms with invisible flooring and minimal light, etc etc.
Make the items interesting and fun to use, not just useful.
More swords :D I've always liked the thought of link being a sort of adventurer/blade master type of guy.
Make the Master Sword a melee/projectile weapon again :P
More chicks ;)
Catchier tunes.
Give link a goddamn guitar. No flutes, no ocarina's, no wands. Give him a manly acoustic XD
Make EVERYTHING epic :D Make gannons powers completely unbelievable, make a charged light arrow seem like the goddamn vector cannon from ZOE2 Explore that Japanese creativity :P
Something of the equivalent to grav boots in Ratchet series. Walking up walls is awesome. Period.
From 0 to KICKASS in .stupid seconds.