We have one, and some of our kitties like cruising around the house in it... but I've never tried zipping it shut.

Not sure how they'd handle it if they felt confined.
We actually bought the stroller as a substitute for the standard carriers, because two of our cats weigh more than 20 pounds, and it's
very hard to lift them in a carrier. It makes vet visits a lot easier.
I never have tried taking any of our kitties out for a recreational jaunt, though, because around the time we bought the stroller, a neighbor's unleashed pit bull followed me down home from one of my walks, growling and shoving his mouth against the backs of my knees!

After that, I lost all interest in going outside for awhile. And even though that family has moved away, I'm painfully aware that the fabric and netting on these strollers is not strong enough to protect a cat if a big dog like that decided to attack.
Also, since all our cats seem to be comfortable being indoors-only, I sure don't want to get them interested in the
outdoors again!
