Scott Mitchell does a good job of articulating the theory and benefits of designing effective, reusable ASP code. Unfortunately, in the end the book lacks sufficient breadth and depth in many topic areas.
Upon purchasing this book my expectations were somewhat low (how much information can you pack in a 300 page book?) considering the extensive topic. Although the book is a good overview, I suspect most developers would rather spent their time actually designing reusable components rather than reading about why they should design reuseable components.
In the end, I would say the book is worth the read but level your exepctations.