I had a bit of time today, so I upgraded my "big" W7 laptop using the in-place method: run the upgrade program, let it do all its checks and downloads, then wait a couple of hours while it grinds away. It went smoothly enough, no problems in the process. The only installed application that had to be removed was Microsoft's own Defender anti-virus, probably because the process installs its own version of that. Apart from that everything else works, it's pretty much the same under the skin.
The default is to link your user account to Microsoft's Windows Live service, and synchronize user settings between computers that way, but you can turn that off and log in as a "local user", under Control Panel / Users. I only have one Windows computer, so I have no need for "single sign-on" of that sort.
I'll report back if I find anything interesting.