While I like the interface, I found choosing colours for the page to be surprisingly difficult, even though I have extensive knowledge with similar SaaS.
Customer service is often abrupt and could be more helpful.
Most frustrating is the pricing plans. I upgraded from my free account to a paid one, and then lost access to tons of "plugins" which I wasn't aware of until my customers mentioned crucial information (like my prices) suddenly went away.
Also, it seems they lock away what many would consider basic features (like showing pricing or needing to approve appointments), call them "plugins" (they're not third party apps or actual plugins, like Apple or Shopify include in their app store) but just really basic stuff YouCanBookMe gives away for free.