It took less than 5 minutes from the time UPS delivered this until my cats were on it. Assembly is quick and easy. I haven't had any stability issues and my cats are large. They don't use the top perch though... it's pretty small. But they love the taller scratching post. The cubby is just big enough for my 16-lb cat to curl up in. This is a great perch/scratcher for in front of a window.