I installed Windows 8 in Virtual Box at home on my desktop with all the Direct3D/2D/etc. enhancements enabled so that it got the absolute best performance. I ran it full screen across all 3 of my monitors to give it a real honest trial.
I absolutely hate the stupid Metro start menu thing. It's so random what was made Metro and what wasn't. You are constantly switching between the Metro thing and the Desktop. It's just horrible on multiple monitors because the Metro start menu thing moves all around to other monitors whenever you move a window (do we still call them that?) between monitors. The hovering on the corners and then clicking thing to get the "Start" button is so much slower and non-obvious than clicking Start (granted using the Windows key or CTRL-ESC is faster than both).
Also, everything says "Tap here" now instead of click, which just secures my belief the design team spent almost zero hours thinking about non-tablet users (and I'm not even convinced it will be a good UI there, but I don't have any touch screen devices to test it on).
It is worse on Windows Server 2012 where every tool you use is not Metro, but the Start menu still is, so you are constantly switching. They redesigned the Server Manager tool to sort of look Metro-ish, but it's still a "legacy" desktop app and it offers less functionality than the previous version is pretty awesome in the way it centralized management better than the 2008 Server Manager (I added this after using it for a while longer).
The way I see it, Windows 8 is half-finished like a lot of things Microsoft has released recently (i.e. Vista).
At least they are offering an upgrade price of $39.99, presumably because they are expecting no one to want it.
I just don't get it… GET OFF MY LAWN!
Also, this video of some guy's Dad using Windows 8 is true if not a little staged: