I've just spent a couple of days playing with Windows 8, and I can't really see the point. Metro is constantly pushed into your face in a most annoying way. So you spend a lot of time in the desktop anyway. I just wanted to be able to disable Metro (or make it completely secondary), and get the start button back.
There's a reason it's been a staple in Windows for the last 17 years - it's one place you can go to and find whatever you want from the beginning. Instead, Win 8 there's constant messing about to find what you're after. It's just quicker to use the explorer to go through the file system to find what you want, if you can remember what it's called.
I found things like searching for the apps you want in Metro is clunky, with stuff not being found, but with duplicates of stuff all over. It's like someone opened everything on the start menu/program files and then listed it all out at once. Nested and collapsible program groups have been abandoned in favour of just throwing everything at the screen at once, and then removing that functionality from the desktop view.
The upgrade install doesn't really work. It takes hours (more than four, instead of about 20-30 mins for a fresh install), and stuff that is supposed to work, then doesn't, and needs re-installing anyway. Some stuff still has compatibility issues. After the upgrade, stuff that was working after a clean install (like the weather widget or online music shopping portal) isn't working after an upgrade. Yes, upgrading a Win 7 installation successfully seems to have broken Microsoft's own Win 8 online shop/metro apps.
It makes no sense to me to force a tablet/smartphone GUI onto a desktop where it's not needed and doesn't work that well, and then remove the start menu to force people into Metro. Really, they need to put that start menu back, unless MS are expecting us to make all our own shortcuts and program groups for everything and put it on metro where it will just drop us back into the desktop.
I'd be happy with Windows 8 as an incremental upgrade at a reasonable price, if MS reinstated the start button/menu and if it didn't have Metro/appstore constantly getting in the way, but I'm not interested in an OS that makes things harder to use than the one before it.