Neither of us had ever had geese before we 
acquired Lysander and Desdemona. 
Here are some husbandry techniques, basic information, and 
miscellaneous experiences we've had as geese owners.
LIFE SPAN
Many geese can live to be 20-25 years old.  If you get a goose, be prepared to have it around for quite a while!  Actually, be prepared to have a couple of them around for quite a while, as geese by nature hang around in groups and need companionship.  If you don't want a breeding pair, it's a good idea to get a couple of females, as males may fight.  We just happened to get lucky and the two males we had got along very well.
When Gabriel developed problems that turned out to be fatal, we learned from our bird vet that humans have messed with the genetics of some breeds to the extent that they no longer have normal lifespans.  Gabriel was an Embden, and that breed is used for meat, so their genetics have probably been altered more than some other breeds.
LIVING QUARTERS
Our geese are in a large, fenced enclosure with shade ramadas, several water containers (including a large one for swimming), seed containers, and a large patch of grass.  I've seen people keep geese without giving them water to swim in, but that doesn't seem fair, as they love the water. 
They like cold weather and rain and never seek shelter from either.  On really cold mornings, we've cracked a layer of ice in their swimming container and they've jumped right in, looking quite happy.  They don't like heat nearly as well, so we make sure they have shaded areas and plenty of water and set up a mister on really hot days.
Their enclosure does not have a top over it, but domestic geese generally don't bother trying to fly away.  Most of them get too heavy to even attempt it.
DIET
For some time, our guys ate scratch feed, grass, and various greens, such as collard and turnip greens, spinach, kale, etc.  Recently, because Josephine's feather condition looked so poor, we switched the a food formulated specifically for waterfowl.  It's not available at feed stores in our area, so we mail-order it from www.mazuri.com.
Shredding the greens a bit and floating them in one of the water containers makes them very happy for some reason.  I guess in the wild they would eat various water plants.  Desdemona loved mealworms, but our other geese haven't shown much interest in them.
It's tough to get anything to grow in their enclosure unless we put little fences around the plants, as they are quick to eat whatever we plant.  We do grow a patch of grass for them, as they love to eat grass and need plant material in their diet.
MAINTENANCE
Unless you are lucky enough to have a pond on your property, geese take a fair amount of maintenance.  Most waterfowl are rather messy creatures and geese are no exception.   We have to empty, scrub, and refill the water containers and tidy up their enclosure on a daily basis.
INTERACTIONS WITH OTHER ANIMALS
Dogs and geese are not a good combination.  Our geese are kept separate from our dogs.  They are protected from coyotes as well, but none of the other predators in the area are likely to view them as suitable prey.  They're too large for a domestic cat or any of the local birds of prey to mess with, though I'm sure a bobcat could take one if there were any in our area.
Male geese may fight with each other, though they seem more apt to get along if they've been raised together.  I know several people who keep geese and ducks together and have no problems.
Interestingly, I have twice seen a raven land in the geese's enclosure and both times, Lysander chased it away.  Gabriel reserved his wrath for the dogs, whom he hissed at through the fence.
SUITABILITY AS PETS
A few geese are reasonably "cuddly";  Desdemona, for instance, liked to be petted and got into my lap on more than one occasion.  Others, like Lysander, are civil but do not want to be touched.  Still others are responsible for giving geese a reputation for being nasty and aggressive.  Gabriel fit into this last category during breeding season and I had some ugly bruises to prove it.  All in all, I would say they are not good pets for young children.
There is also the Volume Factor to consider.  Geese are loud - and some species are incredibly loud.  The Embdens I've known have not been too bad, but the China Browns are another story.  Lysander can be heard for great distances and shrieks so loudly he sometimes makes my ears ring.  Keeping geese within city limits is not likely to make you very popular in your neighborhood.
USE AS WATCHDOGS
People often comment that geese make excellent watchdogs, as they are alert and quick to sound the alarm - at top volume - when anything out of the ordinary occurs.  That is true; however, in our experience, they tend to sound the alarm whenever anything occurs.  They honk just as loudly when we come home from work as they do when they see a stranger walking down the street next to our property.  They honk when the dogs come near their enclosure, they honk at wild birds, at the wind, at each other...  You probably get the point.
If you're really serious about guarding your property, you'd be better off getting a dog. 
BREEDING
To see a picture of a goose egg, click here.
[This story is also related on Desdemona's Medical page.]  As a general rule, we don't breed our animals.  We were, however, hoping that Lysander and Desdemona would produce a gosling.  Desdemona began laying eggs not long after the geese came to live with us, but she didn't sit on them.  After several months of her abandoning the eggs, she finally laid a single one and sat on it faithfully.  Male geese don't sit on eggs, but Lysander guarded her and kept her company during the 30-day incubation period.
Right on Day 30, the egg hatched, but our excitement was short-lived.  The poor little gosling was badly deformed and could not have survived;  he was born without any muscle or skin from the neck all the way down to his legs.   He had to be euthanized.  Desdemona didn't seem to recognize him as her offspring, probably because he didn't make the right noises or behave like a normal gosling.  This was a blessing, as she did not miss him. 

She didn't try to hatch any eggs after that.  We don't have any history on Lysander's and Desdemona's origins or breeding, and we now wonder if they were siblings.  If there had been a great deal of inbreeding in the group of geese they belonged to, that might explain the chick's deformity.