Windows 10
The part of the Business School I now work in seems to live and die by meetings, and these meetings are organised using Outlook. I have been using my trust Fastmail account, and whilst it's okay, the calendaring functions (for people looking up my availability) are too messy—they would all need to adjust their configuration.
So, I have bitten the bullet, drunk the Cool-Aide and installed Office 365, and to do that I had to install Windows 10 on my old Debian laptop. Que sera. It's taken me about two weeks to get most things sorted.
Still …
… Outlook is a pig of a programme. It's bloated. It takes me loads of keystrokes to do what would take me one in Fastmail. The only thing that is worse that Outlook IMHO, is Sharepoint.
For the life of me, I can't figure out how to get Emacs to download my calendar from Outlook (well Exchange) and put it in my org-mode Agenda. Grrr.