Although the graphics imply that it will be a combination of Twilight Princess and Wind Waker, I would like Skyward Sword to be more on the Twilight Princess side because Twilight Princess is a mature, well thought out game. Though I prefer Wind Waker because of the childish feel to it and the ease of playing it, I want Skyward Sword will be a big step up from Wind Waker, though, a little teeny tiny baby step back from Twilight Princess.
In a Zelda game, I like for it to be childish at times, but with a very deep plot and I feel that Skyward Sword hasn't exactly shown those needs. To me, it looks a lot like Wind Waker with a couple splashes of Twilight Princess. Wind Waker is a very excellent game to play when you're new to playing Legend of Zelda, but it's just a little bit too childish for my taste. Twilight Princess, on the other hand, is a teeny tiny bit too dark and there wasn't exactly childish moments in the game.
So in conclusion, (and even though I want Skyward Sword to be a lot more like Twilight Princess, but some splashes of Wind Waker) I think that Skyward Sword will be more on the Wind Waker side than the Twilight Princess side because of what Nintendo has shown us so far. But I won't be giving up my hopes for a deep plot with Wind Waker touches in Skyward Sword!