This was my first order with Wayfair. It didn't arrive on the day it said and the tracking didn't work. I emailed Wayfair who were quick to respond and look into the issue. The order arrived 4 days after the original date and some of the shelves were damaged. I emailed Wayfair again and again they were very quick to respond and address the issue, offering us replacement parts or financial compensation. 
On the whole the bookcases are decent quality for the money (if they hadn't arrived damaged). The issues I encountered would have put me off ordering from Wayfair again if it hadn't been for the customer service. This was outstanding, they responded extremely quickly and addressed every issue brilliantly.