I was put off by the first part of the book. The author spent too much pages on obvious things to promote the book but did not say anything new. Fortunately, the rest of the book is much better.
The work “influence” is very broad. Sometimes the author conflates it with “persuasion”, which means “moving by argument, entreaty, or expostulation to a belief, position, or course of action”. Influence, or persuasion, as presented in this book, includes rational arguments as well as manipulation of subconscious mechanisms, with the latter as a focus. It is more useful for short-term relationships such as sales or happenstance interactions (such as with hotel receptionist), rather than long-term relationships such as teamwork, family, and leadership.
The techniques and principles presented in the book are not novel; most of them are well-known in interpersonal relationship studies. However, the book is still valuable because it integrates these “laws” into the “influence” framework, and provides practical guidelines and examples on their applications. Furthermore, the book presented may scientific studies to back up these “laws”. To me, these studies not only provide evidence, but also indicate quantitatively the efficacy of these techniques. Some techniques are very effective, while others appear to be marginally useful. Such quantitative information is lacking in most popular books and articles.
Overall, it is an interesting book and a fun read. Since it covers many concepts and information, it should be read repeatedly if one is serious about increasing influence power. And the book is well written to make such repeated reading enjoyable (again, except for the first part).