Over here, we're using the Botnet Golem to quickly pop into a system, zombify a bunch of enemy fleet ships after the AI has wasted its first volley on our fleet, and retreat it immediately before they reload. Also works to clear out AI fleet ships surrounding guard posts, when the stars align and there's nothing to stop the Golem.
So while we do take it out of the garage, we only give it tasks it can actually handle...which isn't much. The zombies themselves are absolutely laughable, coasting into enemy systems one by one to slowly trickle into the reprisal pool; and when the Devourer Golem swings about, those previously impressive-looking Zombie patrols just disappear in a flash.
All things considered, it's not worth the trouble. I like it in theory, and it can be used to some effect during early and parts of mid-game, but later on and especially towards the end it's just plain useless.