I've used several appointment booking softwares over the past year or two, but I've always found that most of them have some kind of quirk, or bug which prevents me from using them long-term and of the others, they're simply too expensive for my needs
Acuity Scheduling is genuinely the best of all of those I've tried and I intend on sticking with them because their software 'does what it says on the can' so to speak.
It's very simple to use, even for technophobes and the interface looks good too, the backend is easy to understand, plus rescheduling appointments is a breeze for both the customer and staff. Best of all, AS's pricing policy is very competitive.
I don't buy purely on price, because I firmly believe that in general, you pay for what you get, but it's a factor in my decision and the AS range of prices meets my strict personal criteria.
All in all the software receives 5 stars from me and deservedly so.
Try it, I think you'll be glad you did.