Adding a couple of things:
Boot time. Windows 8 is much faster than WIndows 7 in boot from cold hardware. I can scarcely imagine what a some of the future devices I will get my mitts on with SSD will do.
Battery life. I have heard from other testers that it is better. My test machine is pretty efficient anyway, and I have not run it all the way down yet.
Tablet and desktop. People whine this is a problem, but after a few months of use it is something I really like now. Key point here is the ability to run classic applications and drive them with a mouse for finer work.
Metro convergence. This is something that is hard to explain. It is not as good as Windows Phone, but the last release is getting there. All the information presented in one spot without having to launch a unique vendor App. If I click on the Contacts or Pictures hub, I have access to Facebook friends and photos as well as my own Photos stored locally..and it is presented cleanly and in an aesthetically pleasing manner.
Tip for folks that complain about not knowing how to start: If you don't feel like lifting your finger to swipe the logon screen up, then you can click the mouse button once to reveal logon.
There is more, but I remember the exact same reaction here on El Reg to Windows 7 when I was talking about how good it was before RTM. Gloom and doom about another Vista. Next release of Windows will see the same cycle. "WHY DO I NEED WINDOWS 9!? I am perfectly happy with Metro."
Guess we will see if customers buy it...there is the test.