Not difficult to set up - came with the hex key to do all the screws.  The screws are big & sturdy, there aren't a bunch of different sizes to sort out, and they went in to pre-drilled holes just fine.  Just took me about 20 minutes to put together by myself. There are lots of different levels for my cat, plus a couple of hiding places for him to feel secure away from people and my dog.  I have it in my basement as the top level is now level with a basement window that he can look out of.  All in all, right now it's nice and sturdy, has lots of scratching post options at each level.  Probably could accommodate 2-3 cats, if I had them.