Weekly view probably is the most useful one: you can span throught multiple days but you have more details than the monthly view.
Full day events are in the top part of the agenda, while ones with a start and a end time are positioned on the grid; if you click on them, you'll enter in edit mode and if you hover your mouse over them you'll get some quick information.
If you want to add a new item you can click on thebutton or, if you want to add it "on the fly", you can click and drag to set the start/end time and then insert the title; then you'll be able to add more information later.
You're on the phone with a customer of yours and you have to move an appointment?
Remember that you can drag&drop it to move it to another day/postpone it and you can resize it to change its duration!