Haller sets out to describe the racism in the late 20th Century. The book is not an easy read. There are several chapters that read like biology textbooks. The scientific jargon seems repetitive and overwhelming. Granted the title implies a scientific study; but Haller reproduces way too much from his primary sources, needlessly filling extra pages.
Haller definitely establishes scientific attitudes of racial inferiority, 1859-1900. He covers the major authors - scientific, philosophical, and political. What appears to be missing is any contrary data. The data was there. Some of Haller's best analysis is comparing studies of cranial capacity to demonstrate that the average cranial capacity of Africans is in the middle of many different ethnic groups, and usually above East Asians and Malayans, a quandrum for several of the authors Haller references. Furthermore, Haller includes tongue-in-cheek moments like when he points out depending upon what grain is used to measure cranial capacity will lead to different results. He also seems to enjoy repeating the absurd claim that Africans will die from laziness and exposure to advanced ideas from Caucasians.
Noticeably absent in the book is any contrary data. There are no abolitionist writings, even though Haller does include philosophical and religious "research" in later chapters. The lack of opposing views seems to shake the value of this book. Perhaps because readers have to shuffle through chapter after chapter on medical observation, cranial measurements, and so forth, they are eager to read something less scientific, and will accept his research.
Overall, Haller has produced a lot of primary sources. However, I do not feel that his analysis or discussion is good. It is difficult to identify a thesis. Instead, the book appears to be more of a characterization of the pseudo-science of the past under the guide of academic rigor.