Can't speak about geese, but they are beautiful! I have runners, and they are wonderful. Ducklings are a bit of work, and ducks like to dabble around a bit. They are considered messy, but in a good environment they don't have to be a problem. They need plenty of clean water to drink, and water deep enough to dip their heads into. They are great foragers, and eat slugs, Japanese beetles, grubs, and flying insects. They are fun to watch and full of personality.
My mom's family used geese as guard dogs, and I have been menaced by a goose or two when visiting farms, so I don't plan on having them any time soon. Again, though, they are beautiful. There is a goose forum here, too, where you may get better help.