Good, but not great
I bought this after trying dozens of litter boxes over the years. It does work, I have 2 house cats and I can clean this once every two days now, still has the same litter in it after 4 weeks, best to put a lot of litter in to begin with. You must use good clumping litter though, Worlds best works well.
The only complaints I have is that some litter escapes from the join between the top and bottom piece when you roll the box, but not a lot. Also the plastic around the removal tray is a little thin, so bends easily, I have my box pushed up tight in a corner to stop my dog getting in to the litter and it has bent the plastic slightly.