As I am a former employee of the Theodore Roosevelt Medora Foundation, both summers during college and 4.5 years full time, this book told some stories I had heard already but also filled in a lot of very interesting history that I knew very little about. I really should have read it while I still worked in Medora. I would also recommend it--more mildly but still--to residents of Bismarck who are interested in history. Relatedly, my occasional search queries about the book led me to stumble upon readnd.org which seems like a nice resource for finding books related to North Dakota.
The biography is well split in topics between personal and Gold Seal. Likewise the balance in coverage of Harold's two marriages is good. The almost entirely linear narration means that cuts to a backstory (a literary device that I find quite annoying) are graciously kept to a minimum, and I enjoyed the frequent foreshadowing at section and chapter ends. Though there were a few that I couldn't figure out even with my substantial existing knowledge-base.
I'll say that my great rating does include that the topics covered are of great interest to me, and for the average person it would probably be ranked as a good biography.