Hi, I'll bite on that, haha! I am a software developer and have developed enterprise software on Windows since the Windows 3.1 16 bit era. I am also an avid user of Linux and MacOS. I have worked on pretty much everything from kernel development on PC/Smartphones, to middle tier services, to GUI development. While Windows 8/8.1/2012 Server were abysmal in my opinion, MS is finally getting it right after some trials and tribulations with Windows 10. In my opinion, the biggest issues with the current revision of Windows 10 are:
1) All the extra processes that have been bundled and turned on by default (telemetry, adware etc.) - no biggie, if you understand the operating system, you can turn most of this stuff off. I'm not arguing whether these services are useful or malicious, I just don't want/need all these processes running, hitting my disk\CPU\RAM, and needing to be updated etc.
2) Windows Update - abysmal. Takes way too long to update a machine, likely because there are so many extra things to update and manage (see number 1). Mac and Linux are miles ahead in this area as far as frustration goes. At least when I update these operating system, I have some idea of how long it will take. Linux repositories are still the first and the best "app store" for a PC operating system. In particular, Arch and AUR are my favorites.
3) The Cortana/Search bar function is always unresponsive on many PC's just after logging in because background services are still preparing the backend of the search daemon etc. You pretty much have to have a speed demon of a PC for it to perform well on startup.
Other than these issues, I am liking Windows 10 in its current form. Don't get me wrong, I could do the same for Mac and Linux, LOL.