Muscovies have masses of personality and are a hundred times smarter than chickens. Although mine have never been aggressive, I would think twice about allowing small children to handle them: the males can be very strong and I have dislocated a thumb trying to catch one. Mine lay almost daily during the Spring and Summer but begin later in the season than other fowl. They are pretty miserable in the snow and have not enjoyed recent Winters. I've never allowed them free range of the whole garden (too many foxes) but, having seen them strip their sizeable run of vegetation, I am not convinced that's a good idea anyway despite the snail cull.
Being a breeder my self i would say to everyone who has a smaller garden to buy these birds. they dont need water to swim in and they kill all snails and insects very good birds..
Muscovys are really hardy birds, my brother has 7 and he has no slugs what so ever, pure white one's are nice too.
I had a muscovy that sat on a nest of 18 eggs last yr in February through snow, driving rain and gale force winds that came straight off the sea- very hardy resiliant birds, good mothers, very friendly and make good table birds.
This breed is good at hoovering up all the slugs and snails in the garden very very quite and good egg production and are a good table bird.