We've never had an indoor cat. Eugene is six months and still inside. He's Mr. Personality so we're hesitant to show him how to use the cat door. On the other hand he's a bit of a terror sometimes. He can leap to great heights and we often catch him trying impossible leaps. He crashes a fair amount. Not in love with the litter boxes. We have two because he hides and gets locked out of the kitchen regularly. And lastly there are his kills. Although I'm thrilled there are no guts, blood or feathers, we do lose a ton of toilet paper.