I updated my laptop, and it went well. Minor glitch as one of the applications no longer liked my video card, but that was an application issue and installing the Nvidia drivers fixed it anyway.
I usually prefer a clean install, but this time around it turned out that two applications I use a lot don't support Windows 8 just yet and tech support said they couldn't help me move the licenses to an unsupported OS. At that point my only other options were a dual boot, which I deeply despise, or a VM, which always feels rather clunky. So in place upgrade it was, and I'm happy I did. The fact it took considerably less than it usually takes me to reinstall and reconfigure everything prompted me to do the same on the desktop PC, also with good results.
YMMV, of course; my boot times were nowhere close 5 minutes, so our setups may not be comparable after all.