They are nice in the early game, and do well against rebels and barbarian types. If you don't like bribing rebels, you can keep a few in your garrison (cheap upkeep) and use them to pummel the rebels that keep popping up. Haven't tried using them as town garrison just for the purpose of maintaining public order. Does anyone know if the dogs (not handlers) count as troops for this purpose?

I haven't seen any path issues attacking cities, maybe since the dogs themselves don't have a formation this helps (or maybe I don't pay enough attention to them once they get going).