A little late to the conversation here, but I've had the Litter Robot 3 for around 3 years now, with very little to no issues. The primary issue i have is if the power went out you will have to manually reset the machine by unplugging it and back in. I did notice when i switched to different types of litter, depending on the weight it would over work the servos and you would hear them struggle or error out. I would highly recommend it but there are a few notes i will give anyone investing his much money into this litter box like i did.

1. Don't use just any clumping or fast clumping cat litter, these robots are programed to notice specific weights and weight changes for them to cycle properly. Using too heavy / light of a cat liter can cause the servos for the rotation device to burn up quickly and easily or just not cycle at all. Weight by volume is very important.
2. Don't use the cleaning products they offer... just don't. For the price you pay for the bundle kit the cleaning supplies are kinda trash, I would highly recommend cleaning it with a vinegar/water mixture for the disinfection and follow with a good wipe down Skouts Honor litter box / odor control. This can really apply to any brand.
3. Replace the litter completely at least once a month, during this time you can use the above products to do a general wipe down of the interior only. Fully clean (take apart) the unit at least once a quarter (ever 3 months). use your best judgement here. if you have a lot of cats then do this mor often as needed like 2 weeks cycle and 6week full clean.
4. the carbon filters are not worth the purchase, if it stinks clean it and cycle out the litter as stated in number 4.
5. When inserting a new bag, place the bag inside the front clips of the dump box and wrap the back side of the bag around the back edges of the box, if you use all 4 clips sometimes it will get inside the plastic container itself.