Easy to assemble &  very sturdy!  This tree could be GREAT if the 3rd floor was a little smaller.  It is almost the same size as the one with the hole in it.  There is not enough clearance for the cats to move from the top of the hut to the 3rd floor.  The side pouch isnt secure enough for them to jump out of it onto the floor but it is perfect for them to curl up in.  If the 3rd floor was  2 inches smaller, my cats would be able to move up and down the tree without any problems.  
I would recommend this tree for skinny cats!