Eddie, our 15lb cat, seems very happy playing with it.  We added another tunnel to the end of this one and another cube as well.  It proved to make a pretty impressive area for him to run through and out the various openings.  As he is a large cat, I will add a small mat to make the top level more stable when he jumps into it.  Eddie is quite pleased with this product.  Meow! (Thank you in cat.)