I have a litter-robot. Works like they say it does. No tines to get clogged up, it spins. Totally keeps the smell down/gone. Mine is 2 years old and still going.
Expensive yes. But we live in a very old house with a basement we cannot let the cats into, no spare rooms, and no room in any bathroom. I keep it under the main staircase in the front hall. (thats how limited we are with any litterbox)
I had two cats using it for the first year, one was 19 pounds. Now I have one cat. I can go away for 10 days and do not have to worry about it having to be cleaned. Though the pet sitter does keep an eye on it.
Many years ago I had one of the normal automatic ones for short time. Started out great but after a while it was just gross. I preferred scooping daily to trying to clean the thing.