--Update--
Bumping this up to 5 stars. Our kittens are now about a year and a half old. They use the tree daily, including the condo, and it still looks brand new.

--Original review--
Our 5 month old kittens love it--they scratch at the posts and hang out in the hammock and condo. The condo is a bit on the smaller side as others have noted, so I'll be interested to see if they continue to use it as they get bigger. The 4 stars instead of 5 is for that reason.
My partner was able to put it together in less than an hour without any assistance