Then there's the forced update system, which allows you to define a time interval where it won't automatically install updates, but it can't be set to more than a 12hs window. It just feels like an OS that thinks it knows what's best for you, but it actually results in an inferior experience compared to the previous versions due to its limited configurability.
I haven't played around with the registry and internals that much since Win'95, just because it adds all this unneeded overhead without any option to remove it from within its own settings.
Don't get me wrong, it certainly works and I'm getting used to all its new features and changes, but Win10 makes it really hard to optimize it to your specific needs for seemingly unnecessary reasons, so I can understand why people want to stick to their Win7 or even Win8 installs.