Not bad. I haven't read any of the other books in this series, but this one seems good. I understand the lack of specific detail, given the source material, but I was most interested in how "cleaned up" the story of Sacajawea would be.
The answer wasn't bad - the book definitely acknowledged that she was likely sold to a man about three times her age, that she probably didn't get to choose whether or not she WANTED to join the Lewis and Clark expedition, especially while pregnant, and that her life was far from pleasant.
But it also uses the text of the expedition's journals to demonstrate the respect her companions had for her, and how Clark berated her husband both for hitting her and for not sharing his reward with her once they returned home.
So it was a more balanced look at her story than I was expecting, and that's good.