Using Classic Outlook on Windows for personal email, calendar, and contact management
I rely on Quick Steps for productivity. With the additional ribbon items, I can't just click on my Quick Steps! This is a MAJOR productivity issue. Outlook365 is ancient, and hasn't had any significant UI improvement in years. It can't even remember my calendar view. Outlook365 doesn't have email reminders or duplicate reminders, but the web version does. It also can't manage a Google calendar very well (no reminders.)
Unfortunately, there are no competing desktop calendar products. So we're stuck with it until you get VERY comfortable with the web version, but that doesn't have as useful reminders and snooze options. As it is, I have to use three apps on my Android phone to get the functionality I need from email and calendars.