Kurlansky starts by saying that salt is ubiquitous in human food production and storage, and then goes on to show it. I was certainly aware that it was used widely, but didn't really understand how widely, and Kurlansky does a great job of slowly revealing the bigger picture of salt production, transport, and use. The sense I had by about midway through was that Kurlansky's job when gathering material for this book wasn't so much in finding good information, but rather choosing what to include, and what had to be cut. As such, there are lots of fascinating details and good anecdotes. There are recipes for many different things (including garum!), and they usually don't feel out of place or like jarring transitions between sections, which are mostly fairly short anyway.
If there is anything to knock about the book, the biggest one was the inclusion of material from his previous books, Cod and Basque History of the World, especially the latter. This is mostly early on, but I remembered it enough to comment on it now, so it was pretty obnoxious.
Another thing that could have been expanded upon is how salt is used in nature, either macro- or microscopically: there's talk of animals following trails to salt licks, and humans then following the animals, but no discussion of how they know to go, or how they use the salt they lick. These are both really petty complaints, especially since the book is already 450 pages and doesn't really need to be longer. Definitely recommended.