Pros: You will cook wiser
Cons: You wish there was even more information.
Umami is what I would consider an essential book, What people think Umami is and what it actually is are two totally different things. I've heard people say it's the taste of goodness or some other philosophical phrase, but no actual knowledge of harnessing it. It's science, not mumbojumbo hippy chef crap.
if you don't know what glutamate, inosinate, and guanylate are, they are the building blocks of Umami, and should be kept in mind when creating any recipe. This is science and food at its finest. Umami doesn't just apply to Japanese Cuisine, it applies to all cuisines, and is the 5th taste amongst Sour, Salty, Sweet, Bitter.
Seriously, I pity the fool who doesn't go out and buy this book