Upside: Absorbent as all get out. Will literally suck the piss out of the cat if it gets a chance. Absolutely no odor. Easy to scoop (assuming you don't get the the Mongo Chunks size, which are about a quarter inch cubed -- stick with hte small pellets). Last about half again as long as traditional litters. And they're white (at least, at first...).

Downside: Because they agressively attract moisture, they attrack the moisture out of your cat's feet, and therefore can stick to the feet of cats that have sweaty paws (you laugh, but there are such things!). So they can end up un the damdest places; the number of such places having a high correllation coefficient with the number of damdest places the cat itself may end up in. Also, tend to be more expensive. We use it all the time, and the expense is by far worth the clenliness. YMMV

You can tell when they need to be changed because they tend to break down into dust. And the color changes from the aforementioned white to about the color of honey.