I updated to Windows 10 about 3 days after official release - on my main development machine. It feels polished and finished to me, and most stuff worked after the upgrade (I had to run repair on SQLServer 2012 and Visual Studio as was getting message about a missing DLL).
Seems to me most reviewers and users (outside of the reg, which isn't a typical user-set) have liked it.
Windows 8 to me felt half finished and ill-conceived - but I'm loving 10, and it seems faster to me.
I'm looking forward to what they can do on the phone, where 8 worked much better than on the PC.