The original vision is the artwork done for the original Legend of Zelda, and the "feel" of the first 3 games.
Gameheadz portrayed the forest where Miyamoto grew up as the birth place of the Legend of Zelda. I don't presume to know that they were speaking the truth, but I am inclined to agree. Many artists take dreams and visions from childhood to directly translate into their art.
But the thing that makes me feel most strongly about the proper style of Zelda is simply Miyamoto's views on gaming, and the previous games he has made. All of his games have had a familiar feel about them. They are all lighthearted, and very cartoony at heart. I mean, look at A Link to the Past, and compare it to Wind Waker. The graphical style of the games are very similar. Hell, compare Pikmin, Mario, LttP, and Animal Crossing to Zelda: OoT. can you spot the oddball there?
Miyamoto once said that after creating the SpaceWorld 2000 demo for Zelda, he really didn't like Link or the series anymore, and that's why he felt he had to bring the franchise back to its roots.
As far as reinventing Zelda goes, I think that has to do with the setting and plot of the game. The game's setting was very different from earlier incarnations, and the plot was much more deep and epic in scope.
The thing is that when I play the game, I can literally feel the spirit of Miyamoto behind it. I don't care if Shiggy makes 100 games more, I will always cherish Zelda: Wind Waker as Miyamoto's greatest achievement.
Now, I will admit that when I first saw the Zelda trailer alongside the Mario Sunshine trailer, I wasn't impressed at all. I hated the style, and I didn't like the game at that moment. I grudgingly grew to accept it, but when I saw the E3 trailer that Nintendo posted on their site, it was love at first sight. The second trailer was presented in a very different way, and it showed more of the game and its style to me.