First, the surprise:  I had NO idea that something billed as a "foldable bookshelf" would have to be assembled.  Frankly, I wouldn't have bought these units had I known they had to be built; I would have purchased other, assemble-your-own bookshelves.  Also:  This is not a one-person assembly job; the instructions insist on two people -- and they're right.

Second, the pleasure:  They are sturdy, and don't bend under the weight of my books and the wide top provides an additional work surface.