Pros: BLACK EGGS! also good foragers, don't need a lot of food, alert for hawks, funny/entertaining
Cons: their high activity destroys and erodes some things
Swedish ducks are so funny. They love to tunnel their big noses into the dirt, and dive underwater for several seconds before popping up someplace else. They stand on "hawk alert" when airplanes pass by. They are smart too, though not as smart as geese, which they copy and try to "graze" grass (they have managed to do this by grabbing a tuft of grass, quickly twisting their heads to tear it, and swallowing). They lay good eggs, usually white but our two black females lay "black" eggs, darker than anything else I've seen IRL or online. Here's a picture.
It actually looks a little lighter in the picture than it actually was. Unfortunately I gave them a little too much white oyster shell. For some reason the eggs have gotten progressively lighter, bluish-grayish. Still neat though and very tasty. Recommended if you want a nice dual purpose or pet duck.