The 8.1 update/upgrade process is just as I feared: simply a full new OS install over an existing OS, with all the mess that that entails. I updated from an ISO file, but what I see on the web suggests the Store-based update is just the same, other than the download and initiation mechanism.
What collateral damage did you see after the update? Did you update from the Store or by other means?
"Keep your settings", yeah right. It wouldn't even keep the wallpaper! Firewall half doesn't work (plus a host of "unknwon devices" in Device Manager, probably related), VirtualBox damaged, QtTabBar a bit funny, touchpad drivers gone (meticulously tweaked in the registry), graphics driver untweaked, Explorer/shell settings and tweaks gone. That's on a superficial first look. I'm afraid to try running any of the major programs installed. But hey, LockHunter still seems functional, and other than "You have new programs to open this file type" nags the image viewer is still associated.
On top of that I can't activate, nor even find a Microsoft phone number for activation issues. The 8.1 setup doesn't accept 8.0 keys (why?), so I used a setup key I found on Microsoft's site. My assumption is that activation doesn't work because the setup key was of a different type than the real key I have. Way to go, Microsoft.
I don't have time for this mess right now, but even restoring a System Image of the pre-upgrade isn't easy to do because 8.1 won't restore an image created with 8.0! Since I can't find the Win8 disc, and the ISO is on a computer that's currently without a PSU, all I have to do is find a torrent for the ISO (computer didn't come with an OS disc, of course).
And Microsoft now plans on releasing updates in this form, and almost at the rate of Chrome "major" updates? Oh, dear.
EDIT: Haven't tried these, but for Core and non-KMS (I think) Pro setup keys for 8.1 see here:
Edited by shae, 22 July 2014 - 09:29 AM.