I like to think of this book as a cross between David Swenson's Ashtanga Practice Manual and Yoga Mala. Scott's book only cover's the primary series, while Swenson's book covers both the Primary and Intermediate Series. The big difference is the level of detail Scott offers with getting into and out of each pose. Swenson offers three to four variations of every posture displayed, while Scott only displays the "correct" version of each posture. While Swenson gives a great break down of each pose in the Sun Salutation A & B, Standing, Primary, Intermediate, and Finishing series, Scott gives explicit detail of how to get into and out of every pose. Swenson gives pictures (and pictures of modifications) of each pose in the Sun Salutation A & B, Standing, Primary, and Finishing series. Scott offers some philisophy and opening and closing prayers (similar but not as detailed as Yoga Mala). Scott also offers tremendous detail on sychronizing the breath with each movement. It is a more visual representation (but not quite as detailed version) of what a person would get reading Yoga Mala. In addition, Scott gives the Sanskrit count of each movement of the two Sun Salutation series.
Overall, Scott offers a tremendous break down of the Primary Series, each pose is explained in enough detail to allow an advanced practioner to appreciate the subtleties of linking breath and movement, while being easy enough for a beginner (along with attending regular classes with an instrutor) to read and gain a deeper understanding of the Primary Series. The opening and closing prayers are good too (and not found in Swenson's book). I would suggest using Swenson's book to see each pose and find a modified version (if necessary) that suites your skill level, while using Scott's book after you feel confident in your practice to go deeper into the Primary Series. Again, this book is a great way to gain further understanding of the Primary Series and would probably make a great teacher's aid.