I have had the book on my bookshelf for a while now, but I have only started reading it in ernest as the end of the season is in sight. It is a great reference if you are either new to cycling, or new to the weight room. The book provides specific exercises that target your core, arms, neck, and legs, and shows how each exercise performed in the gym also helps you on the bike.
I like the author's approach reminding cyclists that they need to strengthen more than just their legs, and that flexibility is also an important component to your overall fitness as well. His anatomy lessons appear before each chapter's "target" area, and gives you the basics of their structure and function. It is straightforward enough that you don't lose interest. I feel that the strength of this book are the illustrations ( yeah... I know what you are thinking) but they are remarkably clear and useful, showing the correct posture for performing an exercise, as well as highlighting the muscle group that the exercise is targeting. Sovndal also provides variations of most of the exercises - so that if you have difficulty or find that the original is too difficult, there are other ways to work the intended muscle group.
If you have spent a significant time in the weight room, you might find the book a little remedial. If that is the case, you might want to try "Weight Training for Cyclists" by Ken Doyle & Eric Schmitz, which has less of a focus on posture and proper lifting technique, but more overall advice about weight training, proper nutrition, getting enough rest, training cycles, putting together a comprehensive training plan, etc, etc, etc.
Hope this helps,