I was one of the lucky ones who was able to update to Windows 8.1 before the installer was pulled from the store. To be honest I just started the update and left the machine, so I am not totally sue how long it took. An educated guess would be between 30 to 45 minutes.
So far the verdict is pretty positive. The performance is very good, despite me using old hardware, and curiously I lost none of my apps.
The two things I enjoy the most is boot to desktop and the ability to set my wallpaper as background when I am in the metro environment. Boot to desktop is pretty self explanatory, so I will not dwell on that.
The wallpaper functionality really works for me. Normally I can’t wrap my mind around switching between the two environments – it just seems unnatural somehow. However, now that I see something recognizable the heuristics of it makes it more natural and easy to make the switch. I probably use the metro environment a lot more now compared to earlier. As I am looking into getting my grubby hands on a Lenovo Yoga, I think I might actually use the metro environment on a more regular basis.