I have 3 monster Toulouse that free range around my yard / pond - this is what they do for me:
Cut down on mowing my grass - I only have to mow once every 2 weeks which saves diesel in my tractor.
Haven't had a cattail in my 1 acre pond in years - saves me the trouble of pulling them myself.
Any food scraps from the kitchen go out the back door and are consumed in minutes.
They're eggs make great omelets.
Cheap to feed as they mostly scavenge their own food.
A few cons:
For some reason they like my concrete sidewalk and that's where they poop (alot)!
They won't weed your garden but consume everything in it. I have a 32" fence around mine which keeps them a bay.
Most geese are very noisy. I've had many different breeds but Toulouse are very docile and quiet, which is why I like them over any other breed.