Hi 5 to Codepeople.
The plug-in is really powerful and easy to customize. As for the support.. A member stood by me during 3 days to solve an issue I had. I'm now using their appointment booking calendar plug-in on my client's web.
5 stars are well deserved, for both the product and the support.
And concerning the paypal feature in the free version... Guys, what else would you use? :D