We've owned our Litter Robot for about 7 months and we just love it. I was worried at first about how our 2 cats would adjust to it since we have one younger kitten and one older, senior cat who is a bit sensitive but they've had no problems. We did have to wait though for our kitten to grow to be at least five pounds, but that didn't take very long! The instructions also include tips on how to help your cats adjust, like placing it by your other box and leaving it unplugged until they get used to it.
The Litter Robot takes a variety of litter. I've only tried clumping types like World's Best Cat Litter and also a different brand of clumping pine litter, and they all worked out fine. I replace the bottom drawer's bag twice a week, and completely change out the litter every 2-3 weeks. It is a bit hard though to empty out all of the litter in your Litter Robot if you accidentally overfill it, which I've done a couple times. It's amazing though to not have to scoop and clean out the old fashioned way, so I do recommend it!
Cons: easy to overfill, slightly loud, a bit pricey, rather large (for a litter box), awkward to move (when cleaning the floors, for example)
Pros: accurate sensor, accommodates a variety of litter types, large enough for bigger-sized cats, no more scooping!!!! (this one for me outweighs all of the cons :) )