At the core of the advances are more memory (64MB), integrated WiFi, and a faster CPU. However, the key feature is the battery life, which is supposed to be six hours with the WiFi going full-tilt-boogie. Not bad if it is true, my Toshiba certainly doesn't get that.
The uphill battle is going to be on the screen and software fronts. Microsoft's OS has always required higher density screens, which has made it more appropriate for some applications that need more screen space.