I don't regret it on my laptop my nettop SFF computer. Why? Because those things were quite slow, and Win 10 rejuvinated them. Feel much more responsive now.
However, my main desktop actually has a reasonable CPU and doesn't need the Win 10 speedup, and after using Win 10 on those other machines for a while, I've decided I'm just going to leave the desktop on Win 7 for now.
The Win 10 speedup is really nice, but the OS overall feels unfinished, and an odd mix of disparate UI styling.
And I still cannot use the Win 10 interface to create new users. It's just broken on my two machines. I have to use a command to get back the old admin user interface, since they removed it from the Control Panel too.
The only problem with Win 7 is that it doesn't support the touch frameworks, so if I remote to it, I won't be able to interface with it on my tablet properly. However, it's moot anyway, since my Win 7 is Home, not Pro.