My cats were tentative when the tree was finally assembled.  Then they discovered the sisal and it's been a love affair for them ever since.  They take turns sleeping in the tallest niche, thwapping the dangling mouse around, and chasing each other from top to bottom.  I love the softness of the light blue fleece on each level--my only wish is that there would be some kind of cushioning or padding underneath the fleece.  I'd like to give an extra half star to make this 4 1/2--the lack of padding under the fleece is the reason for the not quite perfect score.