Nice systems. (And unlike Samsung's latest offerings, these are distinct Microsoft designs and are not knock-offs of what other companies are shipping.)
I especially like their large Surface Studio. The idea of being able to quickly fold a desktop-style workstation into a flat drafting-board-like surface for pen-based interaction is great. I've seen concepts like this, but I think this is the first time the concept will ship in an commercial product. And I love the concept of the Surface Dial - hopefully we'll see some great apps that can take advantage of this device.