Just to say that I've done 6 updates to Win 10(5 Home 1 Pro). All have worked. The little oddities(i.e. not full Win 10 behavior) that my own main pc had were all cured by doing a clean install.
Once you've done an upgrade one you can then do a full clean install if you want as the hardware hash of your machine is automatically recognized by MS once it goes online to activate. The downside is that if you change Motherboard in an upgraded machine you are likely to need a new licence?
One caveat for gamers of a clean install is there is no DX9
(if you upgrade its fine) so you have to boot into safe mode and install it manually to get older DX9/10 and some DX11 games to work.
I can also highly recommend Start10 if you prefer other Start Menu layouts. It has lots of options for Win 7 or 8 or 10 styles and its only $5.
Merry Christmas
Paul M