Handwritten is a collection of exemplary work in the world of graphic design in which the "handwritten" has been implemented as a creative element. Examples range from magazine covers, traditional one-page advertisements, film festival posters, album covers, book covers & other eccentric media/art. What this book lacks in text, it makes up for in insightful streamlined descriptions as to how the authors believe selections "work" as graphic art. In response to a poster in which the artist implemented a "childish" scrawl, they note: "Scrawl is most effective when located with a generous helping of negative space, as is portrayed elegantly in this poster...etc." Rad.
And while you might disagree with their observations, you'll become aware of your own critical eye and identify the aesthetics and styles you most respond to.
Bottom line: this book is worth the money.
Buy it and you'll break out a sketchbook again.