Chin Na is the art of seizing and controlling, and is an element of all Chinese martial arts including Taijiquan. Today, most people practice Taijiquan to maintain health or cure sickness. For the last fifty years the martial aspects of Taijiquan have been ignored, and the art is now incomplete. Most practitioners no longer understand the martial applications of Taijiquan, or even that it is a martial art. For example, the concept and training methods of Taiji Jin (or Taiji martial power), and how to apply internal Qi in the martial arts have become an unfamiliar subject in Taiji societies today. As a result, actual martial applications of Jin and Qi, such as Chin Na or Cavity Strikes, are currently not popularly known or studied. To preserve Taiji's martial aspect, this book presents 85 Taiji Chin Na (Qin Na), the art of controlling an opponent through joint locks and cavity strikes. Taiji Chin Na is one of the four main martial training categories of Taijiquan (the other three categories are striking, kicking, and wrestling / downing the opponent). Of all these four, Chin Na is the most effective, practical, powerful, and easiest to learn. Once you have mastered Taiji Chin Na, you will be able to apply the theory and techniques to any other martial style you practice. If you are a Taiji beginner, Taiji Chin Na could offer you a key to enter the door of martial Taiji.
Even though the author demonstrates applications based on the eight energies and various postures of the Yang style, there really isn't anything uniquely Taiji about this book. Furthermore, all but a handful of the applications are speculative at best, and only work under laboratory conditions. I feel like they tried to force the postures into applications so they could write a book for Taiji players who might not realize that this material has been given a better treatment elsewhere.
It's a good book for joint locks and it works well with blending it into the Tai Chi postures and forms. Yet the Shaolin version would serve just as well. it also has more details. But this one has some of the energy work added in. I would say you only need to buy one of the two books. There are a great number of pictures that help you understand the application of each lock. it's very clear and easy to follow! Both books are great. If you lack the imagination to adapt a technique. Then this one's for you. Enjoy.