Wouldn't fault at all and give a five stars if there weren't those -already mentioned in other reviews- annoying folds which prevent the liner to be flat against the bottom and not trap litter in, and if there were deeper. If you have a large cat thus large litter box, the liner won't go over the sides of the box then get secured in place once you put the top of the box back on. Real shame for they're much stronger than just about any other liners getting easily torn by enthusiastic claws.
A very good idea, but I use clumping litter and I have found that in removing the clumps I have torn the bottom of the bag in several places. They could be stronger and also have draw-strings at the top.
The bags are probably excellent for a standard litter tray, but my advice is don't bother if you have a covered one. The door on my cat toilet won't swing open and shut as the bag gets in the ways, so the litter gets kicked outside the box and makes as much mess as I was trying to avoid by getting the covered litter tray!