Blessings joelop,
For someone that has not worked with yoga I would say this text is not a good place to start. The reason is that it packs in too much information and practices without fully explaining the consequences, problems, and other issues that pop up.
For someone who is familiar with yogic practices, who has gone through a similar process, this text is helpful. In fact, Swami Satyananda has created a pretty decent systematic approach to yoga. If this was the only text available I believe it would be sufficient to guide a practitioner to yoga?s aim of stilling the mind, awakening energy, Samadhi, and so forth. One thing is for certain, Satyananda did not write this book for the weekend yoga warrior ? it is for the person who takes yoga everywhere they go.
I have been working with this text off and on for a year or so, incorporating some things into my daily practices, storing other practices to memory for later on, and discarding others as I see fit. The key is to listen to yourself: body, emotions, mind, energy, et cetera. When you got that down, then working with this book and maybe supplementing it with at least some in class time and other books if possible, will likely suit your purposes ? whatever that may be. The fact that the book has come to you at two different times seems to at the very least hint at some connection between you and it. I would suggest of course that you read some of his teacher?s writings (Sivananda) ? most ? if not all of them are online freely: his writing are simple, truthful, insightful, and very helpful when it comes to working with the mind and dealing with issues as they pop up.
In the end ? you should do what you feel is right. If yoga teaches us anything, it is to listen. And of course, ask questions. I have found this forum has many beautiful yogis and yoginis in it, and whenever someone has a genuine heartfelt question ? there is always someone here to give ear, suggestions, and help whenever possible.
Blessings Be?