It is very stable and lots of stuff for my cats to do.  The only problem is that when there are two cats on it with one on the top level and another on the next highest level, the cat on the top can't get down without either a) jumping on the cat on the next level or b) jumping from the top directly to the floor. I modified it by adding a third level that is just higher than the "open room".  I used a post and aquare "floor" off of another product from the same manufacturer and now the cat on the top can get down without jumping from the top level.  The screws and scratching posts(from the other cat condo) worked perfectly and now everyone is happy.  They should include the third level area with the condo.