I upgraded willingly so the deceptive upgrade practices, while deplorable, didn't really affect me. What does affect me is that Microsoft refuses to let me control my computer. - If you turn off Windows Defender Real Time Protection it explicitly tells you "You can turn this off, but if it's off for a while we'll turn it back on". It turns itself on upon next reboot, it seems. - You can't turn off Windows Update. It…
But here's where it got nasty: the user data was kept, but all of the privacy settings and default apps were reset. Actually not reset, it made you go through the OS configuration screens where it always suggests the default (share all user and browsing information with MS). The configuration was so full of dark patterns: the default is a single button on the screen, but the non default settings are accessed through an underlined link that is not very descriptive. Or turning off tracking is labeled advanced and opens another window.
This was the real scary part to me: if you are not a savvy user and know to turn off these things, Win 10 defaults will track everything you do, including your browsing activity ("to provide suggestions"). These basic privacy settings should not be hiding behind dark patterns.