I set up the Appointy WordPress plugin on a client's Web site a couple months ago. She contacted me today about her disappointing and frustrating experience. Apparently there were a number of problems with their product. When she contacted their customer service she was assured that if they could not resolve the issues to her satisfaction they would refund her for her 6 month plan. When they could not resolve the problems, instead of refunding her $99 as they promised they stopped responding to her emails.
The two largest issues were:
(1) Her Google Calendar appointments were not all syncing with with her Appointy Calendar, so the WP plugin showed her as available during times she was not.
(2) Since she has to account for travel time, her appointments cannot be back-to-back. There was no way for her to put "pad time" between clients. They suggested a work-around for this that would make her Google calendar inaccurate, wouldn't work 100% of the time, and would take more time than it was worth.
The second problem only applies to certain businesses, but the first should be a warning to anyone who was drawn to this product because of its supposed ability to work well with a Google Calendar. I do not recommend Appointy.