If you brood in the house, ducklings are way messier and smellier than chicks (one of the many reasons I now brood in the coop). There's a few things you can do to minimize it but you will have to clean the brooder daily, if not more. But honestly, there are few things cuter than watching ducklings swim in your sink or tub.
As far as adult care, I think they are about the same but it's all in your management style and set-up. I have my ducks and chickens together. When I moved I changed things to make it easier on me. I prefer the coop on ground level (so do the ducks). I like being able to walk in the coop. I find that deep litter is really easy with ducks. If you have ducks only in the coop with DL you have to turn it yourself because they just pack it down. I tried pea gravel and it was terrible. It was good in summer when I could spray the poop off but the whole things became a poopy/ rocky ice block in winter. With DL I just add straw or shavings and the chicks and ducks will disperse it for me. This spring I plan to shovel it out and put it in a garden. I think the choice of ground cover is where some duck owners run into problems.
For water in summer, I have multiple types of buckets and tubs all over the place and everyone drinks from them. In the coop I have buckets with vertical nipples and everyone drinks from those too. The ducks have a kiddie pool that gets changed every couple of days. I got a sump pump and long hose to empty it. Easy on the back and it lets me water the trees with the poopy water (they thrive on it). The pool doesn't get used in cold weather. This year I hope to dig a pond and use the principles of aquaponics to clean the water.
For water in winter, I have the heated buckets and dog bowl. I remove the nipple waterers because they freeze. Sometimes I have to put a board on the top to keep the ducks from try to bath in it. I have a small tub, kind of like a cement mixing tub, that I fill with water for swimming on nice days. It freezes overnight. If it's warm I dump and refill. If it's cold I leave it till a warm day.
So to sum up, no ducks really aren't harder to care for. The big difference in needs is the deep water for washing out their nares and eyes. But I think you really have to plan things out in advance.