I'm a massive fan of .NET and MVC as a development stack and think VS is the bees knees when it comes to my IDE (with a Vi plugin of course). But I'm hugely excited about .NET Core for the sole reason of abandoning the Windows OS. It really is a horror, it comes bundled with crapware which gets reinstalled when a major update is applied, the major updates are foisted upon you whether you want them or not, after a major update they re-pin their own products to the start bar, there is numerous thing you have to switch off to opt out of their data gathering (and I believe there's some data gathering it's not possible to switch off), they don't allow you to uninstall certain software such as Edge, they don't give the user the means to change OS and re-install Windows if your copy of it was bundled when buying the computer, and that's about all I can think of at the moment.

But pretty much everything I listed above is Microsoft willfully doing things at the expense of the user for their own sake. I could list loads of other things that I'd prefer they did another way but I wanted to highlight things that weren't just subjective preferences.