The only thing I could think of that would make this cat tree better would be if the base was a bit heavier.  It looks a little shaky sometimes when my cat plays on the top, but they do combat that by recommending that you position it against the wall once assembled - in a corner if possible.
This is good for my cats, who are 10 and 12 lbs.  I imagine that if they were much bigger they would not fit well in the little box in the middle.  So, if you have a larger cat, I would recommend one of the styles with a larger cat cubby hole, since mine fit just about to capacity in there.  We are all very happy with it though.