I thought the book was exceptional. It provided exceptional insights into the history of the Sioux Tribes. I didn't like the author's portrait of Red Cloud - I thought it was too critical and the implication that he may have been involved in the murder of Crazy Horse - I just didn't like that idea. Admitted it may well be true but based upon other readings from other authors I already had a bias toward his positive qualities. Nevertheless, I love the book overall.
Moreover, other reputable and scholarly historians I have read credit Mr. Hyde as being extraordinarily credible source although he was not highly educated and was indeed basically an amateur historian. Nevertheless, his books are great and based upon wise reading in the area I find him creditable. In my view if you really want to know about the Sioux Tribes you must read Hyde - although this particular book is about basically, although not exclusively about, the Oglala Sioux now at Pine Ridge, SD - and a lot about how they got there.
Good solid old school history of both the migrations and wars of the 19th century Sioux and the experience of the Oglala tribe in particular. This is one of those authors that wears their biases on their sleeve but does it very well so its a stylistic addition rather than a detriment.
Read parallel with Custer's My Life on the Plains: Or Personal Experiences With the Indians, Hyde's book gives needed prespective to Custer's meglomania. However, no one has a clear picture of how the Oglala Sioux lost their land and freedom. (We know who the guilty parties were, we just lack an unbroken trail of evidence.) As Hyde's analysis (first published in 1935) proved, even the "oral histories" of descendants of the principle actors were often faulty. And, sadly, Red Cloud and other Sioux leaders contributed to their own downfall.