Well got my free upgrade and quite frankly I have been having nothing but trouble since. I have the Pro x64 edition and from the moment I tried just going online after Windows 8.1 arrived at the desktop I knew there was trouble. My network began flapping up and down randomly and there was no indication that Intel had updated drivers for my Ethernet chip until I manually went there. Good thing as it seems I lost all connectivity after downloading them and did not get it back until I installed the new ones. Anyway there were many of these incompatibility issues before I finally got everything to play nicely together. I finally ended up doing a clean install of Windows 8, installing all the updates, upgrading to 8.1 immediately then doing a full true image and have that backed up just in case.
There are still problem though. World of Warcraft will no longer run with my Nvidia 3D settings I like to use. For some reason if I load the game, when it actually loads and I make any changes in the in game graphics settings it goes black as if it is applying the settings but drops to the desktop. It keeps running in the background but will not return. Other things like Game Booster not returning to normal mode after exiting a game unless I do it manually etc... I have also lost all reasonable functionality of my Microsoft Lifecam HD-3000. Version 3.6 of the drivers don't work anymore and the new 4.2 only install the driver, no software or even a lifecam.exe in the Microsoft lifecam folder so it's useless unless I get 3rd party web cam software.
I guess I will get through these as other things seem to run ok and with hardware manufacturers going all 8.1 on the drivers etc.. It's probably a good idea to just stay with 8.1 and wait for updates.