We purchased this because it looked more like furniture than a typical cat tree does.  We also needed to give the cat some vertical space since we planned on getting a dog.  We had to show the cat that she could get up on the highest shelf, but, now that she knows, she is up there all the time.  My only complaint is that the top is a little wobbly, and the cat has to be a little cautious climbing up and down.  Nonetheless, I am very happy with this purchase.

Pros: looks nice in house, fairly easy assembly, cat loves it
Cons: wobbly at top, takes up a lot of space