I had one of these with my last cat and she loved it. Would hide inside and then sit on the top to swipe at people when they walked by. I don't have one at this time, but it is great for cats to play. I had a hard time removing the cat hair, except to vacuum it.

Pros: great for hiding and playing

Cons: needs vacuumed to remove cat hair

Every once in awhile I'll see the small shy cat in the bottom hole, otherwise no one uses the inside. It's a good height for the window, so someone is always on it looking out or just napping. If they get wild it tips, but it is more stable than some I've had

Pros: none

Cons: none

With close to 400 cats at the shelter, this is a hot item. It provides a place for a few cats to rest, play, or just hang out. The ferrel cats particularly like this condo, because it gives them a place to hide out. Very durable and easy to clean.

Pros: Durable, easy to clean

Cons: none

My inside cat is young and energetic and needs good toys to play on/with. He loves playing in out of the holes, going to/from each level and scratching to his hearts content!! He doesn't sleep on it very often, but plays and plays and plays!

Pros: the scent (that I can't smell :>)) attracted my cat right away!

Cons: After being pulled on often little pieces of carpet pulled out... making a mess.

Mine don't use it consistently, however every now and then they'll have a little "freak out" and tear around the room. They inevitably end up on the cat condo.
The holes are big enough that even my fat cat can get in.

Pros: Strong, durable, small

Cons: can be pricy