I am very pleased with Windows 10. I am mainly a OS X user, since the first Mac 128. However, I have had to use Windows on occasion professionally and I play several games that require it. I do not claim that I am a good example for others, I run fairly new equipment, with lots of ram (for me, 16GB) and lots of disks (10TB total). I run multi boot, OS X 10.11, OS X 10.10, Debian, SuSE and Ubuntu, Windows 7, Windows 8.1 (couldn't stand 8) and Windows 10. I always apply all upgrades/updates I can find - I love being a beta site.
All in all, on my system with daily use, I have found Windows 10 to be stable, and easier for ME to use than Windows 8(.1). Windows 7 was the first Windows I ever endorsed, I found it to be stable and "easy" to use. I expect Windows 10 to be the second Windows I endorse after using it for another 6 months or so.