I got the upgrade on my $300 3-year old gateway laptop this morning. I'm not an insider and didn't use any pre-release version of the software. The upgrade is still not available for my gaming machine as of yet (I haven't check my HTPC/mid-level gamer yet).
The upgrade process was pretty painless and took approximately 1.5 hours (processor is a B960 2.2 GHz). I was connected wirelessly for the whole thing. I was impressed that the upgrade process was able to identify necessary drivers for the laptop and that everything functions as expected after the install (no question marks in device manager).
The install gives us the return of the desktop interface as king which after using Windows 8.1 for a while seems a little old-school, but I spent most of my time in the desktop anyhow.
The Cortana functionality is pretty cool but needs some polishing. You can set it to respond to "Hey Cortana...".
If you can't find things like device manager, you just type the name of what you're looking for in the box next to the Windows/Start button. You can also go to the "All apps" selection under the start menu that lists all apps including "Windows Administrative Tools" which includes computer management and the like. The upgrade even kept the apps pinned to my task bar. I was able to import my IE favorites into the Edge browser no problem.
After trying the multi-desktop functionality, I am able to see multiple uses for this as a way to further organize the workspace.
So far, I like it. No strange errors either.
I will definitely have my hardware drivers ready on a thumb drive when it comes to upgrading my gaming machine, but my cheap 3-year old laptop upgraded with no effort.