This book is a good book for the repair of bicycles. However, the writing tends to be sparse and direct. While this in its self is not bad, often more writing can help a less experienced reader in better conceptually understanding how the thing works. On the plus side, you will never have to guess which park tool to use as the author references each tool by name and part number.
As another reviewer mentioned, I feel that the Bicycling Mag/Todd Downs book is a better value. Downs has a casual writing style that makes the reading easy. He covers much more information including some history and the pros and cons of different types of conponets. This book includes both photos and drawings, while the Park book only uses photos. Drawings are a plus and they show views (sections or cut-a-ways) that are difficult to achieve using only photos.
I guess the best way to summarize the difference is to say that the Bicycling book is produced by a publishing company staffed with editors and artists. Their sole business is publishing, so they are experts in written communication. Park is a tool company and their manual reads as though it was written by people who make and use tools, i.e. machinists. That's not bad, it just results in a different style of book.
For me, I preferred the Bicycling book as I enjoyed the extra information. Both books seemed good on the technical info...