This is a phenomenal book. I'd like to give it more than five stars if I could. Seriously, if you are interested in this subject, or these subjects, and want to understand them, you need to read this. "These subjects" include the ethical and environmental issues around eating meat, but also the larger issue of how can we feed all these people, and how can we develop a sustainable civilization on this planet?
On the other hand, you don't need to read the whole thing all at once. I haven't yet. The author himself says that the book is denser and heavier than he planned, and "dense" is actually the first word that came to my mind. It's under 300 pages, the prose is clear, the typeface is legible, but there's a lot of lines on each page, and if you're not already on expert in this field, every paragraph is full of new information and involved arguments, so you can't just breeze through it. That's not the author's fault, just the nature of the beast. Fortunately, although there is a theme to the book, each chapter can stand alone, and in fact most of them are versions of articles or talks that appeared elsewhere. If you just read the first chapter, you may find you need to digest that for a while: it's a pretty dense and rich meal. To read, and really digest, this whole book at once would be difficult. You can read a few chapters, spread the rest out over time, keep it as a reference in the meantime. Or you could read the whole thing now, and I'm sure if you read it again in some time, you'll get more out of it the second time. Deep understanding of complex issues doesn't come all at once.
Some vegetarians and vegans think humans should not eat meat, or should not use animals or animal products. To me that's just silly, and it certainly isn't something we can all agree on. Other animals eat us, and use us, and each other, whenever they get a chance. We never would have reached a level of technology that might be able to do without bone and leather tools, whale oil, etc., if we hadn't used them for so long. We evolved as omnivores; otherwise we couldn't have this discussion. Carnivores couldn't even think about not eating meat; herbivores wouldn't think of eating it. Besides, if we're going to put dwellings, freeways, airports, fast-food restaurants and parking lots everywhere on this planet, there won't be any room for animals that don't serve us somehow or other. There won't be any chickens, except a few hundred in zoos, if we don't eat them, or their eggs. (However, I certainly would like to see those animals treated more humanely. Of course, I'm not in favor of putting people, and our stuff, on every square inch of the planet; it's just that that's the direction we're going, and indeed we're almost there already).
The other argument against meat can't really be refuted. It takes a lot more land and other resources to raise the animals to feed a given number of people, than it does to grow enough vegetables to feed the same number of people.
It's fine to say we claim our rightful place at the top of the pyramid, but the top of the pyramid is supposed to be smaller than the base. Our present meat consumption in developed countries is unsustainable, especially if 6 billion people were to try to adopt it. You can't really argue with that (but you can certainly ignore it, or be completely oblivious of it, which is what most meat eaters do).
HOWEVER-- it is not NEARLY that simple, and that's what this book is about. Yes, meat is a luxury. So are chocolate, coffee, and cinammon. Do we have to give up those too? (on the other hand, we don't consume as much of those as we do of meat. On the other hand...)
So should we all grow rice and potatoes, and just eat that? Well, there are serious problems with that idea.
Maybe if we had, or moved in the direction of, an ecologically sound, sustainable way of life, there would be a role for some livestock in it. And it makes a difference what the animals are eating. There is even a role for inefficiency in a well-designed system. It's an incredibly complex subject, already thoroughly confused by simplistic arguments, and that's why the book is so dense.
Ever wonder why Muslims don't eat pork, Hindus don't eat beef? More puzzling still, why is the Muslim forbidden animal unclean, and the Hindu forbidden animal holy? How come Europeans just eat everything, pigs, cows, sheep, it all seems to work out, no big deal? Just to get the answer to that was worth reading the book for me. Here we have a very important, extremely complex subject matter that very few of us know anything about, and there is a lot to know. This is an outstanding way to get up to speed on these matters. It's also very interesting and pleasant to read, at least in moderate doses.
Some of the other reviewers said the book was too long, too hard, too scientific, or just wasn't what they wanted to hear, damn it. That's all true. Even though it's well written and entertaining, it is scientific, and demands some work on the reader's part, and you're probably not going to like everything you hear. As I see it, those are all good things.