How about people with win 8.1pro that upgraded to win10?
I haven't yet updated cause I want to wait if there will be bugs of any kind.
Also when I decide to update to win10 will you loose are your stuff? Meaning I assume I would need to back all my stuff.
I assume its like completely installing new software.
I'm not sure what your exact question is?..I have done two Win8 Pro 64 upgrades to Win10 Pro x64 with no issues,it kept all my software/games etc.
I can only speak for myself but all my Steam,Origin games etc work fine, software wise not had any issues and drivers are all solid, so IMHO it's a polished release by Microsoft for a new Operating System.
As always Microsoft will continue to fix any issues they find in time just like they do with any Windows OS via updates etc, but end of the day I'm glad I upgraded both of my Win8.1 Pro's to 10, just remember I was also a happy 8.1 user as well with no issues.
I will say learning curve is very small from 8.1 to 10, sure some things are different but nothing hard to adjust to.
With regards to UAC I find it best to leave it as it is and not mess with it, it really is not annoying or gives you too many UAC pop-ups like Vista did in the old days, in fact it feels same as Win8.1, UAC wise to me.