I knew someone who was insistent on upgrading to Windows 10. I mentioned to her what I found out about the operating system. She even heard some of her friends having problems upgrading - mainly it would "lock up" and render the computer useless during the so-called "upgrade" process. She succumbed to the pressure Microsoft was exerting on her and finally upgraded one machine from 8 to 10 and another from 7 to 10. The reasoning behind that was the worry that the old OS would "dry up" (which apparently was her way of worrying about security updates finally coming to a halt).
She let me sit in to watch the process of going from 8 to 10. I tried to keep an open mind about the process. After the slideshow which lasted forever (it was still installing, but it wasn't until 10 minutes in that the slideshow finally mentioned that), I watched Windows 10 begin pushing ads all over the place. At the same time, I got to witness it de-install programs the OS didn't like because of "compatibility" reasons. The programs were admittedly minor anyway (i.e. Rapid Storage technology), but the idea of the OS just uninstalling programs without your permission alone unnerved me.
Once the process was complete, she was horrified that her card games had vanished. Hearts, solitaire, spider solitaire, freecell, etc. were all gone. She eventually found it by scrolling through the start menu, but when she booted it up, it began telling her that she had a one month free trial of solitaire before she could upgrade to premium solitaire. We both had the same thought, "So much for "everything is exactly where you left it"!". It took some digging, but she was able to find a free version in the store so she wouldn't have to pay something like 10 bucks a year for a simple card game.
Suffice to say, after that first hand experience, I was more convinced than ever that I'm sticking with Windows 7. I was already one foot out the door with all the news, but seeing the install process sealed the deal for me.