We've been using Bryntum Calendar at our school for about a year now, mainly so admin can create and manage lesson schedules quickly, and it's been a big upgrade from the spreadsheet-based system we used before. The drag-and-drop is probably our admin's favorite feature. Moving a lesson to a different time used to mean editing cells in Excel and hoping it didn't create a conflict, now our admin just drags it and it's done.
Integrating it with our web application was also a lot easier than we expected. The API docs were clear enough that we could just follow along, and on the few occasions we got stuck, the support forum actually had answers or someone responded pretty quickly. Compared to running everything through Excel before, it's saved us a good amount of time and hassle on scheduling. Review collected by and hosted on G2.com.
Customizing the views can be tricky sometimes, especially when it comes to styling. It's not a dealbreaker, just something that took more trial and error than we expected to get looking exactly how we wanted.
The support renewal fee is a little pricy too, ngl. But Bryntum keeps shipping new versions and improvements, so I guess that's the price of admission for a product that doesn't just sit still. Worth it in the end.
Other than that, it's been smooth. It was easy to learn and get comfortable with, so no real complaints on the usability side. Review collected by and hosted on G2.com.