We've had the 120 for about 5 years now. The "cat eyes'' have stopped working. Since I need to purchase supplies anyway (and the Tabby package is on sale!) it makes sense to purchase an entire new unit with a two year warranty. If I sent the unit in for repair, I would wind up spending more when you factor in the cost of supplies, which are included in the Tabby Package. The unit still works in everything but the "Cat" mode.
Our cats didn't require any break in time to begin using the Genie; they just went right in. When it's on, they enjoy watching their "television." One caveat; if you have long haired cats, you should take the unit apart every 4-5 months to clear the hair which will be wrapped around the impeller shaft. I've got the whole process down to 20 minutes, which includes complete disassembly and cleaning of all internal components. This sure beats the weekly drudgery of dumping the litter box, bleaching and drying it!
I've tried other automatic litter boxes but would have to dump the waste manually. Not much of an upgrade! When I found the CatGenie, I was very impressed. As long as we have cats, we're never going to be without one. Now if they'd just come out with a DogGenie . . .