I've had our Litter Robot for a little over a year, it's running just fine and haven't had any problems at all. The piece is a little on the loud side and woke me up the first couple of weeks but given it's size and that it sits in the room next to my bedroom, it's completely understandable. It's like a loud hair dryer going off. You can also just turn it off at night and do a manual cycle in the morning. If I'm at the other end of the apartment, I can barely hear it at all.
I have two cats, aged 3 (7 lbs, very adventerous, playful, ..nosey) and 5 (11 lbs, was feral for most of his life, skittish but very sweet and cuddly once he's comfortable).Both were adopted when they were about 4 years old from the local SPCA. They were comfortable with an open litter pan while at the pound and/or previous homes and I switched to a covered one for about 8 months before the Litter Robot. They took to the Litter Robot quite well, both explored and used it within half a day and the little one still likes to watch it go around or when I clean it. Both cats, however, seem to pefer the pan style and will use that if it's around instead of the litter robot. However, they absolutely have no problems and easily hop into the litter robot when that's the only choice and they both have room in there to turn around in there.
The piece is very sturdy and simple, I slide the pan out and empty about once a week. It's very simple to clean without a liner (IMO) because the litter doesn't always fall directly into the bag, especially at the front end, and I end up haveing to jiggle things around so there's a clean areas to unfasten the liner. It's not much of a problem for me, I just take the whole pan and dump it into a garbage bag and still don't have to touch anything. The pan goes for a quick rinse and soak in some warm soapy water while I clean the outside and stand with a disposible wipe. Once everything is dried, the pan slides back inside with a sprinkle of baking soda on the bottom and it's good until the next garbage day. The unit does get stinky but the smells don't "stick". Once you soak the disposal pan in warm/soapy water and wipe down the exterior, the smells are gone.
When it gets a little smelly, about once every couple of months, and I dump out all the litter. There is a button just for that specific purpose, so you just let the machine do all the work. I spray down and soak the inside with a mild "all surface" spray and let it sit a few minutes before wipeing to dry it back out. I am also buying less litter, I used to have to dump out the whole pan once every one or two weeks. The Litter Robot also uses about a half to two thirds less than what I was using in the previous litter boxes because it's round so the litter pools into the middle and has less "surface area" to spread out and waste.
About twice a year, I take the whole ball and dunk it in the bathtub for a good rinse. That tends to be a bit bulky to clean and takes a while to fill but it's very a basic soak (mostly to clean the screen), rinse and dry.
Two of the problems I *DO* have with this unit are no fault of the company's :
1) During one of my trips out of time, the kitty sitter/friend didn't toss in enough extra litter over the week so the urine pooled at the bottom of the unit. The litter absorbed all/most of it so it was a solid mass but it also stuck to the lineing of the machine and didn't fall down when the machine rotated. Eventually, it'll dry out and fall back down, of course, and it scrapes off easy enough but it's rather *ick* when you think about it.
2) One of the cats is rather energetic when he covers his waste so there is quite a bit of litter scatter sometimes. I can't take off stars and complain about the company/unit because when I brought it, I could see there wasn't a door cover to prevent this sort of thing and I'd rather not have the machine any bigger than it is already! I had to sweep with their previous pan litter boxes too, so it's not really an extra chore or anything.