My cats love this cat tree, but fortunately they are not in charge of their own safety. Assembly was easy, but the base of this tree is VERY unstable - when my 10lb cat is on the top tier, it rocks back and forth like a palm tree in a hurricane. My very crafty husband removed the base and secured the tree to a 4'x2' piece of an old desk we had laying around, and now (to their delight), the tree is usable. 

Don't buy this unless your slow, quiet, cat weighs 3 pounds, or you have the ability to switch out the base for anything more sturdy.