I have used their service to book appointments with my clients several times over many years now! We are able to keep track of all our scheduled events in one place which makes it so much easier when we need an update or want reminders if someone is running late etc..
The customer support has always been fantastic too - fast replies even after hours/overnight (we're still very new users). There's nothing really that i dislike about them but maybe some of you may be interested as well :D Maybe more info could help? They do provide us with excellent reports including analytics showing how busy each time slot was during any given month. It can also show the breakdown by day type eg morning vs afternoon sessions / weekdays versus weekends; this helps me see what works best at different periods throughout the year.