It all depends on how you raise them. My guineas are the smartest of my flock, smarter than my chickens. I know a lot of people have said they are stupid but they aren't. They do have a tendency to run to whatever they think is dangerous but that is simply because they are curious or want to attack it. They always alert me when their is a hawk flying over or a dog that wanders into the yard. They practically saved my sister from a oppossum. The oppossum came out during the day and went towards my sister, the guineas where across the yard and came running to attack it. They are very hardy and forage a lot. They depend mainly on foraging rather than eating what you provide so a lot of food gets saved. (for my fat chickens). They love seeds and do not damage my garden or lawn. The guineas will eat the weeds and trim the grass and eat all the bugs. They free range during the day and come into the coop to roost at night. Guineas like sleeping in high places so you will need a high roost or else they will roost on the rafters or in a tree. I trained my guineas to roost in the coop on a 6 foot roost. They are noisy. Not a pet for close neighbors. I love my guineas and enjoy watching their antics. They come when called and know their individual names. I will call them by their names and whenever I say one particular guineas name, it will stop foraging and glance my way before continuing. If I call them they come running and love fruits, seeds, and veggies. They also love homemade wheat bread. My guineas have always gone broody and raised young. They lay small, beautiful , almost tear drop shaped eggs. The shells are soo thick and healthy that I have to bang them hard against a bowl in order to crack em open. The chicken eggs are weak shelled compared to the guineas. They will eat almost any pest. Be it bugs, insects, lizards. They even go after small snakes and mice.
Most of the time they will run from a dog if the dog chases them but if they are raised around dogs and do not see them as predators then you will have a problem. They love to come sit on my porch and look at their reflections through the window and preen. I would say the only problem is them always running towards the danger if they think they can kill it. Most of the times they think they can overpower almost anything except for hawkes and larger animals. They are super amusing though.