Pros: EFFECTIVE, reliable, self-cleaning, wonderful, did I mention effective?
Cons: I still have to buy supplies.
I have had several automatic litter boxes, and every single one of them required me to handle cat poo in some way. This one does not. They all required maintenance, some more often than others, and I can't tell you how often the "rake" broke on the one I had before this catgenie. It drove me up a wall!
This one connects to the water line (we use it in our laundry room but you can connect it next to your existing toilet as well), and a sewer drain (toilet bowl, another reason we opted for the laundry room, a straight shot to the drain without sitting smelly in the bowl). We set ours to run every 6 hours with three cats, and it works fantastically. We would have run it on sensor mode, but this is actually the same as twice per day, since it waits 12 hours after each visit to re-run.
It needs to be cleaned about every 6 months (they make a "maintenance solution" cartridge for just this event. It is expensive, yes, but not any more so than buying litter each and every week or day or however often you buy it. It works out about the same (in fact, with some proper internet sleuthing, you can find modifications to make it far cheaper). I use a subscription service through a very large online bookseller who's name starts with A and ends with N, and has a MAZO in the middle, which gets me about a 15% discount on the price of supplies.
We find that our cats took to it slowly, and we had to coax them into it by putting a poo into it and letting the cats see where it was. We also had to show them that it was a litter box by placing them into it, and putting their paw through the clean granules so they would understand. It took about a day and they were instant fans. They liked that the bowl was always clean and "fresh" for their use.
I have had errors and problems with it. The biggest problem I have had is that my cats seem to think that the bowl is a good place to put socks. They get caught in the drain system, and need to be pulled out (usually ruined). This is not a design flaw with the box, just a design flaw with my cat's brains... The second problem is that the water sensor gets dirty. This is easily fixed with some warm water and a paper towel. It isnt even nasty at all, especially when compared to the other options out there. The last problem that I have found, which is ongoing, is that the litter tends to stick to paws just a little bit, and they always seem to bring a few pieces of it with them, necessitating keeping a box of granules on hand for the occassional top-off. I'd say I use a box every 6 months with three cats. It's not that bad at all.
Now, the joys of this box outweigh all of the problems. My cats love it, I NEVER have to touch cat poo, it is 'automagical'™ I don't have to worry about being gone for a few days and returning to a nasty smelly home, I never smell this thing. It just (relatively) quietly works. My home doesnt smell of cat urine or poo either. I don't have to lug heavy litter to the trash can, or mouldy poo-filled plastic hoppers, or grocery store plastic sacks of poo, etc. It was simply set it up and forget it. I couldnt be happier.
I do not know why others are so unhappy with it. If you know what it is, and how it works, and you take the time to read the instructions and sales info before you buy it, then you should have no surprises. It works flawlessly, every time. I have had mine for almost five years and it still works great.