It must be, because they appearantly can afford to have time for you when you have a question. You can even reach them with a problem that is even nót their responsibility. Then, still you get a helpfull and decent answer.
It's a warm and refreshing experience to know that their are stil organisations that make a good product ánd keep up a friendly and personal service!
Personally, I think that's not the case with this component. Without being a very clever boy, you will be able to create different content shown to different groups, top-down as well as down-top (so f.e. paying members will no longer be bored with invitations to become a paying member or invitations to upgrade your membership anymore). And it's not even particularly that what makes this a good component.
When you need a third party developer to add some custom php to it, he will find his way on the fly and rsjoomla even made some fields where it can be added, so I will be paying this 3rd party developer nearly only for the work he's done instead of the research/study before.