My review and criticism is likely driven by the fact that the book is nearly ninety years old. Various perspectives and points of view have evolved over time.
As a compliment, the authors did great research, including extensive use of primary sources. It brings the story to life. However, the book is written through the lens of settlers, primarily white settlers, in a process completely disregarding the folks who lived in the region. In this regard, the discussion and references to many of the treaties in the region and at Fort Laramie do not include enough perspective, especially IMO that of the Lakota (Sioux). When one reads various accounts of the history of the region, it becomes obvious how much the treaties were disregarded by the settlers and the US army defending expansion and mining. For a good perspective on such, try reading Joseph Marshall's books. I believe the history is better understood when reading as many perspectives as possible.