"Somehow my cat figured out how to use a doggy door on her own, so I didn't think we'd have trouble with the cat door. But we are.
The first issue we ran into is that the magnet is so strong, it takes some actual effort to open the door. Second issue is that the door is opaque, so she can't see through it to know that what she wants is on the other side. She keeps pawing at the clear plastic on each side of the door. I ended up taking the metal piece off the door so that it doesn't latch and she didn't get quite as mad at me when I shoved her head through it to show her what to do.
After 2 days, I think she's starting to get the hang of it, but it still takes some coaxing to get her to come back inside.
Once she figures it out, I will put the metal piece back in and hope she can still open the door. I don't want that thing swinging in the wind all winter long.
As far as installation goes, it was pretty easy until we installed the brackets that keep the window from opening up. That was a giant pain, but we got it eventually.
Also, don't buy the ledge separately - it comes with the door. And, the screw holes to attach it didn't line up with the windoor because it sits too high on the windowsill. But, I don't need it anyway since there are windowsills."