i was looking for a calendar extension, which would be working as much as possible like native joomla extension - creating category tree, writing events like articles in categories, using native ACL system. Also had to be as much easy as possible, but still offering a lot of features. Its frontend display looks user friendly and its really easy to start using it, without studying documentation and trying to find out how to use it. At last, support works great. Had a problem with subscription and when i used ticket system, my problem was solved in an hour.
For such money is just great, no reason to spend own time developing some some calendar extension when you can buy readymade solution for such money.