First of all, this rating is only about the difficulty of putting the piece together. The unit is well designed and is functioning as needed and described.
Hopefully, this will help you.  Pay attention to the holes for the larger tower as you will need to connect a support bar from the larger tower to the smaller tower. The two sections of the tower merge with a support bar that holds the top shelf and a support bar that connects the smaller tower. If you don't look for the holes that connect this smaller tower you might put it together with the holes on the wrong side.
Also, when assembling the towers it was not clear which was the bottom of the rack and which was the top. The top is flush so the shelf fits across the top, the bottom is lowered from the frame a bit. 
IMO, the feet that come with the unit are not good. I purchased round furniture slides slightly larger that the feet and it gives the unit stability and makes it easy to move about.