Really easy to put together while watching a movie, and the kittens love both the cat tree and the box!  

[Edit] Just wanted to give an update, I've had this cat tree for four months now and my cats are still greatly in love with it.  I've walked in on them sleeping up on the tallest portion where the sun comes in (I've moved it to a new location from the photos provided).  I'm actually very pleased with this purchase!