They definitely require more time than a lot of other poultry. And yes, they are very messy; they play in mud, splash in water, poop about every 15 minutes and they are wet splatty poops.
My set up for my three girls is a pen that is about 16' x 16' and is 2/3 grass and 1/3 pea gravel around a 5' kiddy pool dug into the ground, along with a 4' x 6' enclosed predator proof pen for night time, that is on top of square flat bricks, that I spray off once a day into a drain we set up off one end. their is a small house for them to lay their eggs in attached to the enclosed pen. I usually give the grass and gravel a quick spray everyday as well. I clean the kiddy pool every 3 days ( a lot of people say everyday, but mine don't seem to dirty it up that fast.)
They are worth every bit of effort it takes to care for them and clean up after them, I love mine and couldn't imagine not having them in my backyard!