I call them my African chickens. They weigh about 4 pounds, come in many shades of gray, buff and white, make a loud noise when startled and fly and run around like maniacs.
I think they are cool, but not very good for flock protection.
Our neighbors had 5 guineas but now their guineas have us! I don't even think they go home to roost anymore because I can hear them in the cedar elm in the front pasture. I keep water out for them too.
We don't mind, they eat grasshoppers. We still have snakes though so don't count on them for snake control and they do like to dust bathe in my flower beds and garden!