Anyone who lives in Outlook's calendar has run into popup and other annoyances that can't be turned off or disabled.
When the mouse rolls over a date, an annoying popup opens with the appointment details. It doesn't show you much new information over what you can see on screen: more of the subject, the end date, and if a reminder is set or the appointment is recurring, but no Notes field. In the day or week view with preview, you'll see all of this information plus as much of the body as the time slot allows. The only redeeming benefit of this dialog is on Surface or Ultrabooks - the font in the popup is bigger - and readable - on small, high resolution screens.
Click and Type
The click 'n type feature for an all-day appointment in Calendar's monthly view is responsible for more complaints. First, if you want to create an all-day appointment, a reminder isn't set when you type on the date. If you double click to open an appointment form, a reminder is not set by default, but if you use the All Day Event button or right click on choose All Day event, guess what - you'll have an 18 hour reminder. Click New Appointment and select All day event and the reminder is set for a half a day.
If you copy appointments to other days to avoid typing everything over, it doesn't always work as expected. When you copy an appointment then select another date to paste it on, Outlook thinks you want to type to create a new event. If you paste the copied appointment in the white block, it creates an all-day event using the copied appointment's subject. You need to press Esc to exit this edit mode then paste the appointment to create a new appointment. Using the arrow and page up and page down keys to select the new date avoids the problem, but is more key presses.
Click 'n type comes up every second click (not a double click - that opens a new appointment form). The click you make to copy the appointment is click 1, which makes the click to select a new date click 2 so Outlook thinks you want to type in all day appointment. On the day and week view, a click doesn’t open a box for typing but you can start typing to create an appointment on the selected time period. The month view should work the same way (but doesn't).
Peeks are love 'em or hate 'em. When Compact navigation is enabled, it's too easy to slide over the buttons and open the peek and the only way to close the peek is by moving the mouse off the peek or using the Esc key. I'd like to click to show the peek, double click to switch to that folder.