While you're still able to access the same 'ol half-and-half view from before, you can now have more than two windows open, and it's also possible to adjust the size -- and even have them piled on top of each other, much like what you'd find on a classic desktop OS. We loved Multi-Window before, and adding this new capability makes it even more tempting.
Moving on, the external touchpad is a Magic TrackPad competitor if ever we saw one, with support for all the multi-finger gestures you're used to making in OS X.