It was very hard assembling this, as there are pictures on the instructions, but no written ones. Even the fellow I hire for these things regularly had great difficulty putting it together. At one point, I was sure that I was going to have to ask Wayfair to resend 2 pieces that didn't seem long enough. But almost magically, when we got the shelf unit assembled correctly (there were some wrong moves), these pieces did end up fitting. The result is that the assembled unit looks fantastic! I now have a beautiful WOOD shelf unit! 
It did take about 5 hours to assemble though.