I've tried it today in VirtualBox. Wasn't all that impressed. The Metro UI is NOT a good way to use a desktop OS. I'm sure it has its merits for touch screen interfaces, but let's be honest here: how many desktop users use a touch screen interface? I really didn't like how the mouse was degraded to some sort of second grade interface. This could all change with the final release of course...

That said, I really think Microsoft has gotten it the wrong way round. They want to push Metro onto every user, and the 'old' comfortable desktop is now part of Metro. They should have left the old comfortable desktop, and integrated Metro as app of some sort. A bit like media center is also present in Windows, but its interface does not take over unless you want it to.

Desktop users have different needs from their interface than tablet/touch screen users. In that regard, Apple got it right IMO: MacOS for the desktop, iOS for the touch screen interfaces. Microsoft should learn from their success and not try to re-invent the wheel, because I doubt they will succeed. I'm pretty sure that, if they don't change the way the Metro UI works, and they stubbornly degrade the regular desktop, it will hurt their sales because most users, not in the least the power users, will most likely hate it and will probably stick with Win7.