Skipping the lock screen (and never having to look at the Metro interface) would be great. Of course, the big question will be whether the Group Policy Editor will be available in all editions of Win8, since it's not available in the Home Premium edition of other versions of Windows. Now, if Microsoft is smart, they'll put the Start Menu back in for the Desktop interface. It seems there are a lot of users that want it, and MS just isn't listening. And if they don't put it back in, and if the OEM's are smart, they'll only deploy Windows 8 on tablets, and just make it optional on notebooks and desktop machines. Or include a free downgrade to Windows 7.
I suspect I'd get used to using it if I'm forced to upgrade (e.g. if I have to buy a new machine, and only Win8 units are available), but I'll admit it - I'm an old fashioned die-hard. I still use DOS commands and batch files for a number of operations. They work faster, especially when processing a large number of files, because they don't have any interfacing to do, as opposed to windowed programs that have to update their UI while they're performing the operation.