They at least seem to work. Morale shocks do make units break, and if they're ashigaru they may chain break. Takeda is fun to watch do that with his terrifying trait. They do have the problem that spears are everywhere, and everything on a horse is allergic to everything with a stick, but a couple units seem to be a valuable addition. I find they are far more frustrating in Warhammer Mortal Empires. Unless you're fighting goblins or rats or something, units just do not run. Monsters are where it's at, horses can kind of suck it.