Although entertaining and easy to read, I found it rather unsatisfying. The narrative is vaguely chronological, but contains so many historical and ethnographic digressions and abrupt jumps that one never has the feel of being on a real journey. Keneally is also extremely selective about the way in which he appears in his own narrative: we read about his awe at the immensity of the Colorado canyons, but we never find out how much time he actually spent on his trip; his wife and daughter, who traveled with him throughout the trip, make only cameo appearances; he mentions in passing that he was commissioned to write the book, but doesn't mention whether his trip was paid for or not; and so on. He seems to be trying to combine the authenticity of personal experience with the objectivity of history, while at the same time catering to readers with short attention spans; he is arguably more interested in impressing his audience than in doing justice to his subject material.
I suppose that this sort of criticism can be leveled at most travel writing, and perhaps I'm being unreasonably harsh — or perhaps I've just been reading too much postmodern criticism of ethnographic writing. In the end it is a matter of taste: as far as books on the Southwest go, I'd rather read either Tony Hillerman's novels or Edward Spicer's history, and as far as Keneally goes I greatly prefer his novels.