They're not as mean as undulated or queens, but they get significantly larger than either of those, so they tend to be more destructive than those to.
Aside from them being perfectly willing to kill other fish, any crustaceans, and eat corals, they also have a tendency to redecorate the tank, so you might not find your corals where you left them. Oh, and you have to be careful about powerheads, because they can ches through the cords. And don't keep a heater in your tank, because the fish can break the tube.
Dave