Easy to use and customise, a better offer than any competitors as of this moment. Still missing some customisation options, such as adding once-off availability, or opting out of receiving appointment reminders to your own inbox and just sending them to clients, or controlling your availability from the synced calendar, as well as CalDAV synchronisation to not depend on a major corporation for calendar checking. However, I enjoy the ability to customise reminder and confirmation emails, the recurring booking function (which is better implemented than some of the competitors I looked at), the ability to reschedule an appointment by moving the calendar event (although cancelling doesn't seem to work by deleting the event), and the simplicity of use for clients.