Kind of depends. Jumplists are completely new. The taskbar is more than just the classic taskbar with a new panel or something, so you could consider that a new feature, too. You could call everything a UI improvement. And you could call UI improvements like the new Aero features "Wow features" too. So it kind of depends on what you consider a new feature, and what you would wow at.
But anyway, completely new features are Libraries, Federated Search, VHD support, and a bunch of
other stuff.