Lots of serious flaws in concept
I use it to schedule aircraft and instructors, but the only way to actually find a viable time window is to use the website to open multiple windows for each resource and manually compare busy times.
The entire concept is backwards. Show me available times, not busy times, then show the intersections of those available times.
The app is entirely web based and uses a very slow backend. Every click or keypress is sent back to the server, so it takes minutes just to enter your reservation.
You inexplicably HAVE to enter a comment for every reservation or it does a round trip to the server (slowly) and then rejects the reservation with a pop-up dialog you have to click the button on. Then you click on the comment field, wait for the server, type your comment (usually “aaa”), wait for the server, then submit again.
And finally, the absence of an iPad version is notable for all the pilots who use their iPad as a kneeboard.