I liked the grayscale Twilight, but the final one was more appealing to the eye.
It was stated that during the later stages of Twilight Princess, Miyamoto pretty much just took everything Aonuma was working on, and "upended the tea table." That may have happen between the time that the 2nd and 3rd trailers were released.
I don't think we'll have that problem with Zelda Wii. First of all, Miyamoto already has stated that the game is near completion or deep in development, and he's already stated that Zelda needs big new ideas as well as stating that
TP was missing something. I don't think he'll get scared this time if this Zelda starts becoming more ambitious like
TP looked in that second trailer.
By the way, I'm going to make a thread tomorrow talking about the dungeon design in the Zelda series, and how it can evolve and become more immersive and useful. Look out for that.