Okay. It's more expensive than the average kitty door - by a factor of 100. And it requires human assistance. But the cats love this door. They can see me in the kitchen and they can assess which other cats are about to ambush them on the way in or out.
In all honesty, they liked the old sliding door just as much. But I love this one. I can open it with one hand and without throwing my entire weight behind it. You know the routine: let the cats out, let the cats in etc all day long. Three cats out, one in, two out, one in and so forth.
Not to mention how much easier it's going to be to go out to the deck with a drink and a snack in my hands.