I have seen many of my clients desktop, laptop & ms surface pcs upgrade to windows 10.
have not seen an ms surface have a system issue yet.
I have seen more issues with win7 machines going to win10, than i have win8 or 8.1 machines for the same upgrade.
Overall, genrally id say that about 90 percent of my clients machines so far have upgraded with no issue..
My entire office & home computers are now running windows 10, and im more than happy with it, providing just like win8.1, that classic shell start menu is installed, (
m$ still have not perfected the start menu that we are all used to from win7 and earlier..
ms has brought back the old win7 style backup utility,"backup and restore (windows7)" which allows for scheduled file, folder & system image backups, and a more definable backup routine than win8 file history.
At most, the worst that i have seen required a download of chipset & other hardware drivers, network etc in order for the machine to get back to its original operating speed.
Quite a few application vendors have not updated their code to run effectively on win10, best to check your required apps vendor website to confirm if they are critical to your workflow.
Quite a few email applications have had issues with sending mail through smtp, among other similar issues, these a remedied simply by running the system file checker, which is built into windows.
(admin cmd prompt: sfc/ scannow)
You do get the option of express or customize settings during start up after the upgrade has completed, if you don't like all of your keystrokes, location data etc beaming back to m$, you can disable that functionality by going through the customize option.
I like win8.1 more than win7 , i like win10 more than 8.1
Hope this helps you make a decision..