I first want to start out with; the length of time that these trays last is going to depending on how many cats you have. With one cat, the trays are typically supposed to last for twenty to thirty days. Now, on to the transitioning. If your cat has been using a popular type of litter since you've brought it home, it may take a little for an adjustment, but this is totally up to how the cat reacts to new things. Our cat surprisingly adjusted rather well to the crystals for a cat that has never used them before. They absorbed the urine rather well, so I was pleased with that. The trays are super easy to 'install' and throw away, which is convenient. This specific one doesn't have much of a scent to it, which can be okay, just depends on your preference. All in all, it's been a great three weeks so far!