I love these!! They were a little difficult to put together at first, but they're a blast to play with! Good for dwarves and Syrians, but I don't recommend them for chewers!
Some hamsters will use these, other will not. They keep the cage much cleaner (especially in glass or plastic cages), and you just clean it out once a day, or every other day. Not hard to do at all. :) Both my Syrian and my dwarves used their litterboxes with no help from me, and no prior training. Litterboxes are available at Petco, Petsmart, and most other pet stores. Please be sure to use a dust and scent-free, non-clay litter.
My Syrians climb right out of it, my dwarfs will play in it, but spend most their time looking for a way out. :)
It provides some freedom for the hamsters, allowing them to run around while still enclosed, but not as enclosed as when in the run-arund ball.