Initial assembly and cleaning take a few minutes, but once it is put together, removing and replacing the lid to add more water is very simple.
If you don't want to turn it off, water can be added by dumping it on the lid, but you need to add it more slowly.
Capacity is great. If all you have are a cat or two, you can go more than a week without adding water. 
We love the simple elegance of the design, nothing too cutie...who wants trees or something silly like that.  The motor does have a constant dull hum, which is audible across a quiet room.  The noise is similar to an aquarium pump.