Windows 10 itself is fine. At the end of the day it's just Windows 7 (you'll see lots of old pages and icons if you dig deep enough) with some security improvements and a new UI.
Privacy and ads are a problem though. Not only it sends telemetry to Microsoft (as far as I know it can only be disabled on enterprise), but local search sending data to bing, it installs games and other apps automatically, messages to switch from Chrome or Firefox to Edge... in this regard, Windows 7 was superior.
The good thing is that there are a few scripts and apps that remove some of crap and use better defaults. Since I'm not much a command line guy, I use this tool called O&O ShutUp10 (
https://www.oo-software.com/en/shutup10 ). Easy to use and even using the defaults is already a big improvement.
For those that only need Windows for some tasks and don't want to upgrade to Win 10, consider installing Linux. You can run Windows apps on a virtual machine or with Wine. Ubuntu or Linux Mint are good user friendly distros (if you don't want to jump to something like Arch Linux) and at least your system would be secure.