Our neighbour has one, and I've been looking after the cat for the last couple of days. So these are my thoughts about them from that perspective as opposed to our covered litter box with clumping litter that lasts a month or so.
The electronic litter box didn't seem all that clean still... There was lumps all through it.
It's not covered, so litter goes everywhere still which I hate! This needs to be cleaned up regularly still, so it kinda defeats the purpose.
You can't see how often your cat is going to the toilet. I like to know how often the cat is going on a regular basis. I clean out her litter tray every 2 days probably, and I know how much I should be scooping. If I have no poos, or excess wees, I'll know, and I can monitor her immediately to make sure there's no problems. How can you monitor this sort of thing if a machine scoops it all?
What if your cat has diarrhea?? If it needs to go shortly after it just went and the mechanical thing is doing what it does, and the poor kitty desperately needs to go.... what then???
I like the clumping long lasting stuff. I can monitor my cats toileting habits, it's easy to scoop everything, I can do it every couple of days without it stinking, she can go whenever she wants without getting freaked out by the noise/movement of the mechanical thing, it's covered so I don't have litter going everywhere, she gets her privacy, and it's a heck of a lot cheaper!
I also think $100 is a waste of money, and it's lazy!!