I put this together the other day and was thinking this is going to be flimsy but it's actually very sturdy. 
I wish the mat would be made as 1 pc instead of multiple pcs, would be easier to clean  litter gets under 
I foster kittens and before they are vaccinated i put them in here they LOVE it running all around and up the ladders. There is plenty of room,  only wish the front door pc would be a little wider and easier clip to lock it