Apart from a tortuously interminable introduction which traces, in excruciating detail, the pre-philosophical beliefs which led to the emergence of more rational thinking among the ancient Greeks, this scholarly and (thus) exceedingly dry work is useful in providing insight into the foundations of Western thought. And that's actually saying quite a bit.
It is in the fundamental, largely implicit (i.e., myopic) dualism of ancient Greek thought that we find the seeds of every ill which Western European minds would inflict, and continue to inflict, upon the world. This is not to say that no good has come of Western philosophy. But just as the Greeks divided the universe into two diametric halves, so it is with the fruits of their labors: science has yielded both antibiotics and nuclear warfare, both the Internet and climate change. Nor is the line between so-called Western and Eastern thought necessarily as crystalline as we sometimes choose to believe. Indeed, the influence of the East is acknowledged in this volume, both by the editors and in their sources. But it is clear the Western thought is pervaded by a dualism which Eastern thought more assiduously eschewed.
In short, the early Greeks were determined to break the world around us down into constituent units which could then, presumably, be used to explain all the phenomena which the world presents to us. In this sense, the early rational thinkers were simply taking their mythologizing predecessors to the next level. What does emerge from the frankly tedious introductory material to this book is a clear picture of a people who were determined to understand the universe as a clockwork, presumably with the goal (whether conscious or not) of gaining some control over a mercurial world. Even their pre-rational mythology largely sidesteps broader metaphysical questions of purpose, meaning, psychology, emotion, and so on. Holistic the Greeks were not. They sought for the sources of all things -- laughter, love, even thought itself -- in physical processes, and that's not funny at all.
Why this matters is that when we start to break the world down into components which are separate both from us and from one another, we leave the door open to a great many evils. (Nor is this to say that Eastern thought is some utopian panacea in this regard; but that's a separate issue for another day.) In the simplest, most obvious case, if you and I are distinct and separate entities, unconnected with one another in any fundamental way, one next logical step is for me to objectify you. In fact, my world view has already done that for me, I simply need to pick up the ball and run with it. Before long your personhood means little or nothing to me, and I can easily justify, for example, oppressing you, dehumanizing you, even enslaving you. It is in the writings and thoughts of the Presocratic philosophers that we find the first evolution of this way of thinking from mere superstitious beliefs into an attempt at compelling and persuasive logical reasoning. It is not too much to say that the Greeks, however unwittingly, laid the foundations for chattel slavery, exploitation of every description, totalitarianism, and, by extension, even the Holocaust.
As far as this volume itself, as a book to be read, is concerned, its scholarly approach is predictably dry and redundant. There is a relative dearth of simple paraphrase and practical examples, both of which would have vastly improved readability, and the typical scholarly impulse to split hairs ad nauseam -- often to little discernable reason -- is on full display. Scholars love to fill pages, after all. But the scholarship here is, no doubt, scrupulous, and once you get past the mind-numbing introductory material, the main body of the text is clear enough, if somewhat arid and colorless. It is certainly a good overview of Western philosophical thought before Socrates and his ilk took the reins.