There are two issues I have just found with this plugin:
1. The confirming email (to me) is not being sent when a booking is made.
2. STRONG SUGGESTION: With email notification not working there is NO WAY to tell if someone has made a booking.
PLEASE add a small orange dot with a number beside it in the dashboard against the Appointments tab to ALERT you that a booking has been made and you need to confirm it.
The system needs to draw your attention to the fact something has happened. There is too much to keep an eye on to "know" to go and check it out if appointments aren't regular.