I have 3 cats from 4 months to 4 years.  Even the larger cats enjoy the cat tree.  The smallest (5 pounds) loves the tree.  The two larger cats (15 pounds) can go on the top tier.  2 cats are declawed and have no trouble climbing the tree.

Pros:  the hanging toy, easy to climb from step to step for the declawed cats, the scratching post for the cat with claws.

Cons:  The house is kind of small, my largest cat gets in (somehow) but it would have been nice if it was a bit bigger.  

Overall, a really nice tree, especially for the money, well made, sturdy and nice looking in the house.