My cat is 13 pounds and it tipped over every time she got on it.  I put bricks in the bottom to steady it, then the little and I do mean little shelves would start to bend.  She is not a big cat just medium to small and the shelves were too small for her.  I ended up giving it to Animal Rescue for their kitten play area.

Pros: NONE
Cons: NOT Sturdy, Tips Over, Cheaply Made, Shelves TOO SMALL and HARD