I stuck with Upgrade rather than a clean install. The netbook hardly had anything installed in it. The laptop and desktop both have a number of games I didn't want to reinstall.

The only issue I had from all three installs was a terrible slowdown with The Witcher 3 (literally a slideshow). An Nvidia display driver download fixed that one.

I also turned off or uninstalled a bunch of network sharing/online "features" such as OneDrive and live tiles (in the Start Menu).

Besides the netbook suffering occasional busy pauses while a web page loads (due to 2Gb RAM and weak Atom CPU), Windows 10 seems okay.

My main reason for upgrading is a better OS for the netbook and DX12 for the desktop and laptop.