I owned it for about 4 years. It was great, I still think, but I'm off it now. It really works great if you've been scooping all these years. My cats like it, and no problem whatsoever. It's best for those of us who have multiple cats, and sometimes leave the house for 1-2 days.
We change the waste about 4-5 days. Those plastic pans actually end up costing alot. And I started to line them with grocery bag. Just the same (actually makes it easier to change, just pull out the bag and I end up changing it more often).
However, I've stopped using it about 3 months ago. Just because of the noise. It can get quite noisy at night. And also, I do not like the clumping litter. It tracks all over the house, smells bad, and I was so sick of it. I changed to the pearl litter, and it was wonderful. No tracking, no smelling AT ALL. But littermaid cannot handle it, so I now just use a disposable pin pan. At least it doesn't smell bad anymore.