My experience is that many novices in the field of personality type make erroneous assumptions about the way the cognitive processes operate, and confuse Jung's psychological terminology with everyday word usage. For example, some people mistakenly regard a Judging function as being "judgmental". Berens is careful to define her terms (as one would expect an INTP to do), and her descriptions of the way different cognitive processes are manifested are well-researched and well-considered. She manages to keep her descriptions of the functions content-free, and doesn't confuse functions with traits, which so many people mistakenly do.
An error that many people make is assuming that personality type can be explained by simple addition of the component letters in the MBTI code. Nothing could be further from the truth! An ENFP is not E+N+F+P. Berens makes it very clear that, although she is discussing the cognitive processes in isolation, they must always be considered in the context of the "whole" type. This is a valuable distinction that many people, even qualified professionals, often overlook.
There is an unfortunate tendency for people to take the MBTI and assume that the results it offers are final, whereas even the developers of the instrument will tell you that it is never more than 70% accurate. Consequently, many people labor under the delusion that they are a particular type "because the MBTI said so". These people may then read descriptions of their type and become confused or even reject what they read because it doesn't match their own experience.
Berens very sensibly encourages "self-discovery" when it comes to exploring one's personality type. She believes that each person is the best judge of their own type, provided they are given sufficient resources to determine that type. In my experience, the best personality type results are achieved through a combination of live workshops, experiential exercises, and access to a variety of high quality type-related reading materials. The best resources are those which approach personality type from several different perspectives, including the use of an instrument like the MBTI; explanations of Temperament theory; social styles; and cognitive processes. This book is naturally relevant to the latter.
Another valuable section of this book is Berens' interpretation of Dr. John Beebe's archetypal mappings. I've heard Dr. Beebe speak on several occasions and his theories can be quite complex and daunting. Berens simplifies Beebe's ideas without trivializing them, and makes them more accessible to the layperson.
Although this is an excellent book for beginners, it also contains enough "meat" to satisfy an experienced personality type professional such as myself. While it isn't very thick, it contains more useful material than many texts ten times its weight, and has become an indispensable addition to my training toolbox. There are sections on learning styles, interpersonal communication, and problem solving which are extremely relevant in the workplace, and there are a host of exercises and diagrams that assist me when presenting personality type to my clients.
It's worth mentioning here that Berens' book is a relatively recent publication and incorporates many current trends in psychological type that earlier books will not mention. For example, MBTI training originally stressed four "function/attitude" pairs with a distinct hierarchy, and with decreasing proficiency assigned to each. These are often called the four "dichotomies," and they normally consist of choices between E/I, S/N, T/F, and J/P. Harold Grant's work on Type Development advanced the theory that we achieve greater proficiency with each function in our hierarchy as we age.
Nowadays, the prevailing view is that all 8 function/attitudes are accessible, to a greater or lesser extent, to all personality types, depending on a variety of factors, including age and environment. This new perspective minimizes the sort of stereotyping and "pigeonholing" that often occurred with the old methodology. Berens explains this concept clearly and succinctly in this book.
By invoking Jung's original term "cognitive process" to refer to a "function/attitude", Berens follows this modern trend toward terminology that is more representative of the true meaning of those words. Although she uses the familiar MBTI letters in her book, she is careful to explain the psychological meaning of each in order to reduce the confusion that usually arises when explaining these terms.
This is an excellent book, and I recommend it to the psychological type professional and beginner alike.