The author really made the text flow by providing a high level view and then peeling back each layer to reveal the working of the kernel. In addition, he judiciously intermixed, text (historical, theoretical, practical, opinions) with diagrams, and code segments, which made the book easy to read, and concepts easy to follow.
The code was written in a clean and consistant style, amply annotated with comments which explain what the code does, as opposed to just paraphrasing it. A student or inexperienced "C" coder will see the practical uses of portability techniques, ifdef debugs, type defs, etc., which are frequently ignored in academic works.
Lastly, I'm glad the author resisted the current trend of dumping everything but the kitchen sink into a text just to see how much shelf space he could take up (most professionals are to busy for that nonsense). This is a nuts-and-bolts approach; what are the concepts, why is done, how is done, here's the code (and its all on a companion disk).
If your looking to learn about DOS, kernel implementations, or some good "C" code examples/idioms, this book is highly recommended.