This book is essentially a thorough debunking of various western misconceptions about Daoism, with ample historical detail and discussion about how Daoism changed throughout various eras.

A few of the misconceptions that it debunks:

That there is any real distinction between "philosophical" and "religious" Daoism

Thankfully at this point an idea that has been quite thoroughly debunked and largely eradicated in academic circles, but the echoes of this framing remain in popular culture.

That the Dào Dé Jīng (or Zhuāngzǐ) is the primary, oldest, or most important Daoist text

The book goes into some detail about this, particularly on the Dào Dé Jīng, but I'll let it speak for itself as a summary:

My nuanced answers to the question of how the Nei-yeh, Chuangtzu, and Tao te ching affected later Taoism are as follows:

1. All three of those texts actually played a marginal role in the lives and thoughts of most later Taoists, with a variety of important exceptions, many of which remain little known even among scholars.
2. Many later Taoists, of all periods, looked back to the Lao-tzu and Chuang-tzu for concepts and models that could help them practice Taoism. Others did not, but continued to honor those texts.
3. Few later Taoists read or honored the Nei-yeh — as a text — yet its ideas and practices did become abiding elements of Taoist practice from age to age, as well as of Chinese traditional medicine, and even the cosmological theories usually termed “Neo-Confucian.”

That Daoists kept to themselves and did not interface with the imperial bureaucracy, or were meaningfully anarchist/anti-establishment in practice

While you can find some ideas in Daoist texts that appear somewhat anarchist, and Daoists have been remembered for their role in several popular revolts, they also spent a long time working with the imperial bureaucracy to try to help (and secure patronage from) various emperors throughout history.

That women were excluded from practicing Daoism, or that Daoist practices had a gendered element

This is somewhat more complicated, but the chapter that goes into detail opens:

The roles that women have played in Taoist life will vary according to one’s notion of what “Taoism” is. If by “Taoism” one means the living Cheng-i traditions of Taiwan and coastal China, then women have little or no meaningful role, and have not had for centuries. But, as we have seen, there have actually been many other forms of Taoism. Some we have just begun to recognize, as scholars continue to explore the rich diversity of texts in the Tao-tsang and later Taoist collections.

In the living Lung-men tradition, as in its Ch’üan-chen antecedents and in several earlier Taoist traditions, women have played quite meaningful roles indeed. At times, such individuals were clearly exceptions to the rule. But, at other times, Taoists clearly made sincere, and sometimes successful, efforts to provide relatively equal opportunities to any person willing to participate, regardless of gender or class. In addition, women Taoists of various periods even held positions of influence and authority, sometimes in a formally institutionalized setting.

Over the course of history, virtually all Taoist practices—from self-cultivation practices to “thunder rites”—have been fully accessible to women, and we even know of women who have practiced them. The idea that Taoist self-cultivation practices could, or should, be conceived in gender-specific terms would not arise until the nineteenth century.

That Daoists seek to have a single, coherent attitude towards death

This one is particularly pernicious, since it seems to come from deeply-held beliefs that westerners tend to have about both religion and death. From the book:

The reality is that Taoism is a tradition defined (or perhaps, more correctly, not defined) by people who never saw reason to struggle to achieve agreement about most of life’s deepest ambiguities. Taoists were never laboring to remain true to some “original message,” the way that Christians, Jews, Confucians, and, to some degree, even Buddhists often tried to do. There was no single scripture to which all Taoists through the centuries felt it necessary to tag their beliefs or actions. There was never—at least not past the third century—any Taoist hierarchy that sought to determine doctrine for all Taoists. And there was certainly no effort to achieve or maintain any “philosophical” precision, consistency, or sophistication.

Rather, those who were drawn to understand life, and to express their lives and thoughts, on Taoist terms were a range of people who did not work very hard to find ways to agree with each other. It is not that Taoists of each age “agreed to disagree,” as for instance modern Unitarians profess themselves quite happy to do. Rather, it is that the people who self-identified as Taoists in each age understood and accepted the fact that others might, with some justification, understand life on somewhat different terms. On one level, “Taoism” was, like “Hinduism,” a catch-all category for a wide range of ideas, practices, and models of and for life, which were acknowledged to belong to this loosely defined category mostly, if not exclusively, by the fact that they clearly did not belong to any of the other available categories.

Such being the case, it is not at all surprising that some Taoists over the centuries argued the possibility of obviating death, and the desirability of attaining a deathless state, and even suggested practical methods for attaining some such state. But, while none can dispute the commonness of texts describing or alluding to such ideas, it is true that Taoists also produced and preserved texts that wholly ignored such ideas, others whose perspective on life would seem to preclude such ideas and practices altogether, and even some that ridiculed them, as we shall see. And because those who self-identified as members of “the Tao-chiao ” were, at the very least, content to identify all such texts, ideas, and practices as belonging to their “Tao-chiao” all of them must be accepted as representative of the “authentic” voices of Taoism.

In general, this book does a excellent job of identifying places where western conceptions of Daoism have been more interested in projecting existing western ideas onto a exotic and ancient other, and contrasting that with actual data about what Daoism is and has been. While this book can be quite academic and slow in places, I'd recommend it to anyone interested in gaining a historically-grounded, less appropriative understanding of Daoism.