Too easy but looks nice
Our rescue cat (about 2 years old) figured out how to use this in one minute. On the plus side, he uses it as intended, and doesn't knock it over. On the minus side, I don't think it's much of a challenge for him, but he's one of the smartest cats I've ever had or known. He's also a big (not fat) boy, so he can't push his face into the openings, but a small cat could, I think. It's attractive and easy to clean, but as other reviewers have noted, it needs a heavier base.