Don't be fooled by the precis; this very informative book is really a history of early photography on a mission to rehabilitate the memory of Henry Talbot and not a "story of rivalry" at all. This normally wouldn't be a problem, and certainly would not merit a lower rating, if the actual book were gripping despite the cover lies. But it is not.
Given that the primary author (Roger Watson) is a curator of the Fox Talbot Museum it really isn't a surprise that the book is almost entirely consumed with elevating Henry Talbot's profile as the "real" inventor of photography over Louis Daguerre. Most of this argument is sophistry justified on the basis that Talbot could have published first, but didn't, and that his process involved the negative/positive steps that became the standard for more than a century and allowed endless reproduction of images.
Using that same logic, Talbot is certainly not the inventor of photography since he didn't produce a digital image.
There are attempts to balance the narrative with alternating chapters with vaguely dismissive descriptions of Daguerre's life. But then we are also reminded often that Daguerre was an unreliable mythologist of his own life. Nearly as often, we are reminded that he was a showman who came upon his process by accident and had no papers or notes to reveal his process of discovery.
Contrast this with the paragon who is Henry Fox Talbot, and the bias is pretty clear.
Most frustrating is that this bi-part narrative structure falls apart midway into the book because first Daguerre, and then Talbot, drop out of further work on photography and the technology escapes them altogether. Our two rivals just walk off the field of battle. We are told that there is a rivalry, the authors insist there is a rivalry, and then there is no rivalry.
I am not sure why the authors decided to go this path with the book, I would have been much happier with a high quality and more balanced biography of Talbot alone that also happened to be about the invention of negative image photography. My guess is the premise that these two men (who never met) were locked in a lengthy and terrible struggle made the book an easier sell to the publishers.
Anyway, I learned a lot about early photographic processes and why the US became the first widespread adopter of the technology when it originated in England and France. That was the best part of the book by far.