Having put one of these together I am surprised that it was so well rated.
Ok problems: the instructions are very, very basic… not difficult as such but it’s easy to miss important details which will men you have go back steps. The descriptions of components such as screws is so basic as to be pointless. The amounts of screws is very odd… 
The frame is very flimsy and the cross bar is actually kinda difficult to get it to work.
Overall there are much better quality bookcases in comparable price range.
I would not recommend and would not buy again.