Excerpt from a Hiawatha Bray review
[…] While the coolest new Metro features in Windows 8 are optimized for touch-based devices, the overwhelming majority of users will still rely on a keyboard and mouse. That’s not going to change for a very long time. Metro will work with mouse and keyboard, but switching between apps is often clumsy and confusing. Traditional PC users may abandon Metro altogether and stick to the standard desktop.
But in that case, why rush to convert to Windows 8? Nearly half of all PC users are still running decade-old Windows XP software; Windows 7 is still young and very good. Unless you’re ready for a touchscreen machine, there’s little reason to choose Windows 8.