I find it usable at work by relegating the metro interface to the touch laptop screen and keeping the Windows desktop on an external monitor. It's quite usable like that.. The main thing I miss is the Windows start button and being able to get to search easily from there.
I've been working with it for a week or two now.? I hardly ever encounter the 'metro' start screen in normal day-to-day use - sometimes I hit the windows key just to remind myself its still there :P
I have my common apps pinned to one of the two start bars (one per monitor, yay!) and I tend to use start|run for things like compmgmt.msc, dcomcnfg, eventvwr, services.msc anyway as they work over win2k, win7, win8.
as someone?said recently, arm?someone with the keyboard shortcuts?and have them use it for a while and the 'metro intrusion' (to a desktop user) largely becomes?a non-issue.
It still needs a start menu and I have been using now for a few weeks, and also mainly use just the desktop. A lot fo the 'apps' haven't yet been ported to the metro, so if you want to modify control panel settings for example, it opens up a window back on the desktop, which is really backwards. As you have said you hardly using the metro interface, but that is the start menu replacement. What I find most annoying is shutting down, where that used to be on the start menu. You now have to press alt+ctrl+delete, and then click on the off button and then click again to shut it down. Perhaps they don't expect these things now to be shut down to save power. I will be sticking with windows 7 this time round, but do like windows 8 startup and smaller footprint on my netbook, which it seems perfect for. Just a pity metro apps doesn't work on netbooks due to the 600 pixels height resolution.