It took me two days to learn it's specifics 3 years ago, and after that I never-ever had a problem with it. ItJustWorks(TM).

In this sense it's a bit like Sqlite, which also JustWorks, as opposed to something like Postgres which requires more fiddling and maintenance.

And functionally, it allowed me to create a service-bus topology where multiple processes can post messages on a set of subjects that can be subscribed by multiple other processes (think stock market quotes). This pattern is surprisingly difficult to implement in other message brokers.