I have two large cats - 13.5 and 15.5lbs, so they would easily knock over most trees, and most platforms aren’t big enough for them.  This one is heavy and solid enough that it isn’t going anywhere.  20 lb cats could use this.   Also, the platforms are large enough for my kitties to lounge quite comfortably.  A big plus is it comes already assembled.  I am taking off a star as I am not sure how quickly they will shred the carpet and sisal scratching post.  They’ve already begun to shred the sisal in a couple of spots, and i’ve only had it a week.  
It was expensive, but with very large cats, you need a sturdy tree.