I like the affordability and the ability to take online bookings.
SimplyBook support people respond quickly.
There are multiple issues with SimplyBook's interface.
1. iframes used on websites have issues of popups appearing outside of the viewport
2. links from my website to SimplyBook don't give the option of linking to a specific service
3. if the company hours change to closed for a half day, it changes all of the service times
Even though it's very easy to chat with SimplyBook support, none of them are technical support and are completely unable to solve any problems you contact them about. I've contacted support more times than I can count, both by chat and by email. They typically respond quickly, but none of the problems I've contacted them about have been resolved.
If you offer multiple services or have multiple providers, I don't recommend SimplyBook – it's difficult to set up and doesn't offer enough customization. If you are offering a simple service, SimplyBook would be great and simple to use.
I am using SimplyBook with a client's website so the client can accept online bookings for their services.