Very sturdy and easy to put together and good height as well.
But…
My large cats 9-13lbs had a very difficult time turning around in the boxes.  Shelves  were kinda narrow for turning around or laying on their sides as more than half of their legs hung over the edge - uncomfortable, so they did not stay or play on the cat tree long at all.
Also, none were able to lay down in the bottom square.  
I have put carpeting down on the bare shelves as they seem hesitant to walk on the glossy surface. We will see how that goes. Sadly, as of today, none of three cats are interested anymore - J