While you can specify the hours you're open, the closed days aren't blocked out on the calendar. The client I wanted to use this is a hotel and they're closed Mon and Tue. There was no way to show on the booking calendar that they are closed those two nights.
That problem made the calendar totally unusable for us.
One thing to be aware of is even when you use the free version, they put your listing on their portal. There is a setting to disable it. A year after we abandoned trying to use it on their website, they received a booking from the WebServe portal. Fortunately, they had an opening, but it could have been a big problem. That feature should be an opt in choice, not an opt out, especially when it is fairly hard to find.