I also think the very young, bright, colourful and modern themes are quite a clever step in thinking ahead to the 20th Anniversary. Sure, we've got 2010 and 2011 still to fill, but if they went with another classical, nostalgic celebration it wouldn't make the 20th as welcome as it probably will be. Disney shouldn't get too bogged down in nostalgia.
That said, what are we actually getting? Some lampposts, a couple of shows, a redecorated train, maybe some tat on the Castle. It'll be very easy to avoid. And it's not like they're replacing Fantillusion for Light Magic, which is Disney's classic "let's be hip and modern" effort.
The biggest disappointment for me so far is that the visuals and logos released are so much nicer (and more modern!) than what we've seen from the parks (except the Central Plaza fences). I almost feel the marketing teams should design the entertainment...