Outside of the lack of control, and the spying crap, what really bugs me about 10 is the ugly blocky big UI that you can't really change. There's a few options like the black one, but that's about it. Everything is so big and takes up so much space. Dialogs are too big, window elements are too big. It reminds me of being on a 640x480 monitor. The UI basically negates the real estate gain of being on a higher res monitor. We have it on the church computer and I just find it really annoying to use. I put classic shell so at least the start menu is half decent but the rest of the UI still sucks and is hard on the eyes.
I ended up putting Linux on an older machine which we also use to store speech recordings. I also setup Audacity and such to record right on that machine, so the win10 machine is only really for powerpoint now.