I've been using it since commercial release.
For the first day I found Metro to be frustrating as hell. I nearly grabbed Start8 to get it to revert to something closer the Windows 7 layout but instead I decided I'd spend two weeks on vanilla Win8 and give it a chance. I guess I'm a power user. I spend a large amount of time on my dual-monitor desktop, some light coding, heavy use of keyboard shortcuts, etc.
In the intervening time I've come to enjoy what Metro brings to the table. I spend most of my time in the desktop environment, but as an "enlarged start menu" metro is nice. Using shortcuts I'm never more than one keystroke away from the desktop no matter what I'm doing in Metro, but it is certainly easier to find items in Metro than it was to find them in the old start menu. The large colorful tiles help me pick up the program/shortcut I'm looking for much more quickly.
It certainly has its flaws (the mail app sucks, the dual installations of Chrome and other programs sucks, etc) but it also has potential. I have to say that I'm pleasantly surprised. Now, if desktop goes away completely, it'd be ruined. I don't want to live in a Metro only world on my desktop. But the hybrid is certainly better than I expected.
One last thing: I'm not sure I'd like a Windows RT based tablet. At least not right now. The native apps need more time to bake and the app store is bare.
I realize I'm in the minority with Windows 8, but so far I don't see it as an ME/Vista repeat at all.