Boltz traces the development of the Chinese writing system from its earliest appearance as Oracle-Bone Inscription script to its standardization in the Han dynasty. He also offers a definition of writing in general and a detailed comparison/contrast of the Chinese writing system with other early writing systems in use in Mesopotamia and Egypt.
This book is indeed a very detailed work on the origin and early development of the Chinese writing system, how it arose, how it was perceived and how it changed later on, everything from the earliest characters or pre-writing even up to the writing reforms of the first empreror of the Qin dynasty. Comparisons are often drawn between the Chinese writing and the ancient hieroglyphic system of Egyptian and the cuneiform script of Sumer. A very comprehensive book, but nonetheless hard to comprehend and sometimes even a bit lengthy. Definitely more than just an introduction.
I had to read this for a class. At points, Boltz makes his points clearly and forcefully, and other times, it's hard to understand him through the jargon and dense analyses. The third part of chapter 3, The Multivalence of Graphs was particularly difficult to get through, as Boltz analyzes in excruciating detail several rhyme tables from early China. Chapters 4 and 5, about the legends surrounding the invention of writing and how the Chinese worldview influenced their writing system, were rather interesting, though. I couldn't recommend it unless you're a bit of a masochist, or are reading it for a class (like I am).