Every 3 seconds or so it shoots a nearby enemy within 5km of your ship. It's great to shoot down mines, heavy plasma torps, and boarding party shuttles as it does it automatically for you without any guidance.
Sometime approach an enemy within 5km and don't use any of your weapons you will see the automated defense turret shooting.
Has anyone else noticed that it fires at cloaked ships?
I suspect they are not -supposed- to do that. Think of it this way: if a ship's sensors can't see a cloaked target well enough to fire their main weapons at it why would this little point defense gun be able to?
I honestly think enough people are going to mention this "exploit" enough to get it nerfed eventually.