Lett also makes a very divisive distinction between Fitness and Clinical Pilates, going so far as to claim, "In the case of Fitness Pilates, the dynamic nature of the exercises themselves actually prevents the development of flexibility." What?! Dynamic stretching has been shown time and time again to be superior to static stretching as the nervous system has a built in inhibition to static stretching.
Moving on to the actual stretches, I found the instructions to be a bit confusing. First off, most springs on U.S. made reformers are coded to be Light, Medium, or Heavy and Lett uses weight equivalents in kgs of tension which will require additional research for most readers. Second, many of the stretches are actually Pilates exercises presented under a different name. Anyone who has done even one session on a reformer knows the running exercise, here called "Lying-down Calf Stretch." Russian Splits (an advanced exercise, by the way) is called "Reverse Bent-Leg Hamstring Stretch". Scooter, or Eve's Lunge, is now "Standing Bent-leg Hip Flexor Stretch" which looks suspiciously like the "Standing Bent-Leg Hamstring Stretch".
In the end I am confused about the intended audience for this book. Many of the "stretches" here are actual variations of intermediate/advanced Pilates reformer exercises that could hurt someone who isn't ready for that kind of movement. In addition, most of the exercises require stability and flexibility in other areas than the "target" muscle, so some basic Pilates skill building is necessary to even start with this book. As a Pilates teacher, I feel that this book demeans what I know to be true about classical Pilates exercise. As a fitness professional, I disagree with the premise that dynamic flexibility is ineffective (I see it working in all manner of fitness modalities including Pilates, kettlebells, suspension training, and all manner of functional exercise). And as a client I would find the book confusing for home use, especially since the reformer looks so different and the spring weights are so different from what I know.
I recommend finding a good Pilates studio and a good Pilates teacher to help guide you through the sequences of exercises that Joseph Pilates created and then decide for yourself if you need more stretching. My bet is that after a few weeks you will feel better and more balanced without the additional work.