Pros: Slow, easily caught, good meat, quiet, cheap to feed
Cons: Sharp claws, strong wings, females can fly
We have had Muscovies for several years, and have had a very good experience. While the males do "hiss", it's the Muscovy equivalent of a "quack". They are very quiet ducks and very laid back. Ours are friendly, and will follow us around, Most eat out of my hand and one female trills to me whenever I'm around. They are good around other breeds - ours share a pasture with chickens and Welsh Harlequins and there are never squabbles (at least, not with the ducks!).
They are good foragers, and will "clean" up a yard of bugs, slugs and snails. They eat mosquitoes too. They eat a variety or weeds and can easily forage for most of their food in the spring/summer/fall months, requiring supplemental food only in winter (easy, cheap keepers). I do bring them "treats in the afternoons, to keep them friendly! They require little housing, even here in Washington state, they prefer to be outdoors most of the time. We do not shut ours in at night, we let them choose where they go. They are very cold hardy.
Babies can be tamed very easily. I hand tame babies in the spring to sell as pets. After they hatch, they are brought into the house for a few days for "taming". They are taken for walks outside, to show them "food" and "bugs". The babies come when called and will accept other pets (like rabbits, dogs and cats) as buddies.
They lay lots of eggs, and make good mommas, sometimes even sharing duties with each other. I don't clip wings, and even though capable of flight, ours never bother leaving. When one "accidentally" gets out of the pasture, it tries really hard to get back "in".
They also are fast growers, and produce big meaty birds in a few months. The meat is very lean and exceptionally tasty. Some people compare it to lean veal or ham, although I thinks it's much richer flavoured. We never have a problem selling our meat birds, or our baby "pet" birds (all our babies are called Henry).
We have a steady customer base, and we have a freezer full of meat. This is our first choice for a duck breed (The Welsh Harlequin is our second choice).
Our birds sell as follows
hand tamed babies - 1 week old $10
females - 4-6 months $15/20
Males - 4-6 months $25/35