I saw the initial posts on this site about the Litter Robot and those early positive reviews actually made me go out and buy it. I really regret that decision and I found the Litter Robot by far the worst of the electronic litter devices, worse than Littermaid and Purrfecta, and that is saying something.
Highlights (or Lowlights):
Liquid waste seems to seep into parts of cavity of the tub and stays there causing a permanent stink. I tried washing it in the bathtub several times and the urine smell would not come out. Smellier than any electronic unit I have ever purchased.
The weight-based sensor that tells the Litter Robot when the cat has entered and exited was constantly temperamental and often malfunctioned, just like an imbalanced washing machine. Extremely frustrating to have to reset the tub back to ground zero when I was home, and even more frustrating for the cat when I wasn't.
My cat took forever to adapt to the Litter Robot unlike his experiences with Littermaid or Purrforma, which he adapted to instantly. I don't think he liked the tiny entrance, the tub, and, especially, the concentrated smells inside the tub. In addition, I have a colleague at work who also had to throw out her unit because her cats never adapted to the Litter Robot even though they were fine with the Littermaid.
The litter cleaning ability was iffy. It would often not remove all the clumps (used premium litter) and just let some of them sit in the tub, thus causing even more concentrated smells.
The drawer waste receptacle did not adequately close off smells. Further, no matter what liner size is used, some litter would not go into the liner and land in the drawer instead.
The tub ofen was "off track" and I am not sure if my cat caused it with his movements, or whether it was just bad design. Come to think of it, bad design either way.
The unit has the loudest noise of any of the electronic ones I purchased. It is an annoying grinding gear kind of noise that would wake me up on the second floor with the unit being housed on the first floor.
The huge size and ugliness of the unit are not to be underestimated. There is no way to have this unit appear in a house discreetly.
I chucked the unit after 3 months and will never purchase any Litter Robot product regardless of their claims of fixing any of the above.

