My 2 6 month old kitty's love it - my 7 week old kitty is a little too small to get the full advantage of it.  they did destroy the yarn balls the 1st night but I just tied a bell up there instead and they love it!  It is a little wobbley but if you put it in a corner it is fine.  they use the scratching posts ... but unfortunetly still use my walls as a scratching post as well (but less often) [...] very happy all around