The first time I picked up this book, I was immediately turned off by the obvious character clichés used by the author during the very first train ride (so 20 pages into the book). This seemed an example of a lazy mind-- someone who isn't able to fully flesh out his characters, and so resorts to the tried-n-true.
I will edit my original opinion having had to read this book again for book club. It is not quite as bad as I had feared. I still think it's a product of lazy writing, and that it's an extremely thinly disguised romance novel using a preposterous premise, but I managed to stop skimming it two-thirds of the way through and actually start reading it.
Mr. Fergus did read his American Indian history, and while he has created an environment replete with yet more clichés about the life of the American Indian in the 1800s, he fairly shows all sides of their way of life-- both the lovely and the horrific. The "brides" are more broadly developed characters than I expected, and Fergus is also wise enough not to paint too full a picture of something he would know less than nothing about-- the thoughts and feelings of their husbands and the other Cheyenne women.
But I still disliked it quite a bit. The heavy-handed diary entries and letters, in ye olde American Victorian, were hard to swallow and made the entire novel sound overly fake. I'm not sure I got anything out of this book but a bumpy ride, to be honest.