I had a lot of trouble with the network-of-brokers feature in ActiveMQ a few years ago, which in the end forced us to switch to another solution.

In a later, simpler, project I had issues with ActiveMQ locking up after a certain number of messages, which was solved with an upgrade.

On a whole, I think the quality of ActiveMQ is lower than other open source projects with similar brand recognition, e.g. other popular Apache projects.