I would love to have one of these in my house to the basement to keep the heat/air from escaping. My cats love to go down and hang out, but I often keep the door shut to save energy.

Pros: save energy

Cons: installation

Allows cats to move about without getting trapped behind a closed door.

Pros: access

Cons: none

I like the idea of this for use when the litterbox is downstairs - can then have the basement door shut. But I don't like it when people use it to allow their pets access to the out of doors... too many things can happen unless the pet is supervised!

Pros: access the basement without the door being open

Cons: people use them for outside access

I wanted my cats' litterbox to be in an out of the way place where I didn't have to see it (or smell it) all the time. So, I decided to put a cat door flap on a small linen closet in my hallway and I put the litterbox inside. It took just a few minutes (and some kitty treats) to teach the cats how to use the flap. Now they go in, take care of business, and come back out with ease. I love the fact that the litterbox is hidden and the cats don't seem to mind either.

Pros: durable, functional

Cons: none

We have one of these at our shelter - lets dogs out into a fenced yard. Most dogs don't use it, but some seem to catch on quickly!

Pros: gives access to room without door needing to be open

Cons: none