I'm giving it a try here and writing this post here within Windows 8.
For installation, I burned the ISO to DVD and installed it to a space 500GB HDD I had lying about. Full installation took about 15 minutes and it had drivers for all my hardware apart from the TV tuner.
It sure is quick starting up, which I assume is down to the kernel hibernation. It takes about 8 seconds to reach the app menu after POST and I'm sure this will be near instant with an SSD. On the other hand, they made a hems of shutting down, i.e. Click Start, User, Log Off, then wait..., drag up blind, click power icon and 'Shutdown'... Seriously, there should be a 'Shutdown' on the start menu like every previous version of Windows up to 7.
I do like the app screen. It'll take a little time for me to get use to, but the main advantage I see is that I can fit a lot more applications on this screen than what I can pin to the taskbar in Windows 7. On the other hand, for software not on the app screen, it's a little more tedious to get to as there doesn't seem to be a traditional start menu, at least that I can see off hand other than an A-Z list of installed software on the search screen.
As for stability, I've had to force power it off at least once. :bigsmile: It hung while logging off and I gave up waiting after 5 minutes as there was practically no HDD activity.
The only other issue I came across is that it intermittently ignores my mouse clicks. E.g. I've had a few times where I clicked something and nothing happened and this could be anywhere, e.g. clicking a URL, clicking an app to launch, going into a menu, etc.
Edit: Quick Timings with Stop watch: 9.1 seconds POST to App screen and a further ~2 seconds to IE10 with page loaded. That's pretty quick, considering this is all running on a spinning HDD.
As for shutdown, the PC's power button does the trick.