They tried to destroy linux and free/libre software, and when that didn't work, they started cornering the market and pushing for a move from "Free" to "Open Source." They also support SaaS model, and have made it next to impossible to get a new computer without their mediocre OS. On top of that, their OS is full of spyware, and is starting to become adware too.
But that all pales in comparison to the fact that you do not own your own OS: you can run Microsoft's OS, but you can't modify it or share it.
Oh, and this falls more in the realm of personal preference, but the deliberate lack of customizability is a real pain in the ass.
4/10 OS, only slightly better at disguising its capitalist greed than Apple.
You left out that they refuse to let end users control updates on the system unless they resort to hacky bullshit (and even that doesn't work consistently). As far as I know (and have experienced on Windows Server) this extends to enterprise as well.
Can you explain more? Is that related to the clown gpl guys criticizing BSD/MIT/ISC license and laugh on FreeBSD for letting Apple to do whatever I can't remember?
By most Free Software advocates' accounts, the rise of the term "Open Source" was a deliberate move to make proprietary software less of a bitter pill for us radical digital anarchists: "look, our code is Open and Transparent (but you still can't reproduce or modify it, even if you buy a license)." At the same time, Open Source advocates argued that this was the "Shoe-In-The-Door" for Free Software into the corporate/capitalist landscape—it's not, because it doesn't actually advocate any of Free Software's Four Essential Freedoms (Five, if you consider Copyleft to be essential, as I do).
So basically the corporate world took the concept of Free Software, which was starting to be a threat to their businesses, sanitized it of any actual freedom, and sold it back to devs and users as some kind of magnanimous gesture that they were letting us look (but not touch) the code they wrote. Open Source.
M$ has been essential in this shift. Perusing their github, they make it clear that they're willing to toss projects onto the pile, but make sure as hell to keep the Freedom from infecting any of their larger, popular software (e.g. Office, Visual Studio, Windows). And in return, they get access to whatever code you host on their service, assuming they can interpret vague phrasing in their Privacy Policy loosely enough.