I’ve been running the preview in a VM for a couple of months now (I needed a test machine at work, figured I’d kill two birds with one stone).
In honesty, I think it’s a non-issue. For all the trumpeting, it feels like evolution rather than revolution though I’m sure there’s a lot gone on ‘under the hood.’ I’m not seeing any compelling reason to run out and upgrade from Windows 7 immediately, but I’m not seeing any compelling reason not to either (early-adopter risks aside).
That said, if I was on Windows 8.x I’d probably pull the trigger straight away, Windows 10 is basically Windows 8’s less annoying younger brother. Actually, I know exactly what it is: Windows 10 is to Windows 8 as Windows 7 was to Vista.