Well I'm up and running with 8.1. For me it took about 2.5 hours total, although a lot of that was in the download - however the numerous screens to get going going again were a pain to watch. Lots of dots in circles while Preparing Devices, Getting Ready, Applying PC Settings, Setting up a few more things, two re-boots and finally Installing your Apps. After that it has been a question of updating the Apps and fiddling around to make it run smooth again.
I am using the latest version of Smart8 as well as I still like the Program list that you get with it but Stardock ModernMix seemed to screw up the email App so I have uninstalled that. Might try again later.
So far so good, but it will take a few hours to understand the new features.
From the cursory check that I did I could only find the ability to download it via the Windows Store. I wanted an update or preferably a website that I could download and save the download to but could not find one.
The download was long, my broadband is with BT and I get about 7Mps but as I was downloading just after 12.00pm I am sure that many millions were also downloading it. That wasn't so bad but the constant watching and waiting during the installation was a pain. It was only because I was anxious though, no intervention was really necessary once the download had been finished and accepted.
Currently fiddling with colours, all my apps look garish and in one of the personalisation options I have been busy unticking boxes to stop Microsoft sending me advertisements based on my browsing experiences.
'er indoors has not been particularly happy that I have been sitting here for nigh on 6 hours now, so I am going to quit for a while.
Took me three hours but seems to be ok. A great many screens appear after it seems to be complete. A bit of a pain. And why does it have to send a code to your mobile.
Start button not worth it, and it does take a bit longer to boot up.