I had one for awhile. It eagerly took frozen food without any problems. It never bothered any of my other fish on purpose, and if anything tried to bother it, it would hunch down and raise its dorsal fin until the other fish got bored and left. My yellowtail blue damsel tried to bully it for a couple days, but gave up.
It did kill my rhino blenny, though. The cat knocked something off a table near the tank and it made a big crashing sound, and it scared things in the tank. The waspfish hunched down like usual, and the rhino darted around the tank. Until it crashed into the waspfish. Apparently waspfish are venomous enough that a fish their size running full into their spines will kill the other fish. So, you may not want to keep waspfish with fish that are prone to dashing when panicked, like firefish.
That was a freak accident, though, I wouldn't expect it to happen again.
They're good fish if you can get them to eat, basically. Reclusive, but pretty, and you'll see them reasonably often if they feel safe.
