I'll never think of bacteria the same way again.
We tend to think of bacteria as contaminants, as carriers of disease, something to be eliminated as much as possible. Yong helps us see them in a much different light: bacteria comprise most of the life on this planet; they're everywhere, and only a small fraction of bacterial species cause us harm.
Since bacteria are ubiquitous, it makes sense that evolution would have made use of them. Given how versatile bacteria are, it's no wonder that many organisms harbor them and make use of them to digest food, or produce other important chemicals. You can look at your intestinal flora as a garden or a farm, where you provide food and shelter for bacteria that help you digest, or crowd out harmful bacteria. In fact, we can even go farther and see certain collections of bacteria as separate organs, ones that have been outsourced to a different species, and can sometimes be upgraded, replaced, or discarded wholesale.
But of course biology is much messier than that, and the relationships between living beings aren't as neat as the above may suggest. Nor can pairs of living beings always neatly be classified as "allies" or "enemies".
With his characteristic enthusiasm and clarity, Yong guides us through some of the complexity and wonder of this microscopic world, and I, for one, have a new appreciation for microbes.

One weakness, I found, is that for all the discussion of what bacteria do, the book doesn't really show what they look like. Perhaps the color plates in the middle of the book can be updated in the next edition to maybe show fewer mice and pangolins, and more bacteria.