This book is about the "Em", a virtual human mind with no physical body. Remember The Matrix (1999)? It's like that, but there's no hairless Keanu Reeves in a pink goo pod. Instead, Neo is just a file on a computer, in a server rack somewhere. If we need Neo to do two things at once, we can just copy him (just like movie-Neo copied all those guns). If we decide Neo is 'the best of the best' at something, we might copy him a trillion times, and erase his competitors. The copies are just as human as you or I.
The book is important for two reasons.
The first is that it directly concerns the welfare of trillions of future lives (who may suffer under slavery, total dictatorship, torture, and constant genocide, or who alternatively may live in a paradise of comfort, meaningful work, and total fulfillment). Small actions, taken early enough, could have a big impact on the Age of Em; this book gives us that head start.
Secondly, the book is important in its focus on values. Hanson demonstrates that values are a biological adaptation like any other (the bird's wings, or the fish's scales) and that nature and nurture conspire to ensure that animals end up with productive values. While you may value "family" or "free time", your decedents might be workaholics with no family at all (for reasons beyond their control). As a result, if EMs could meet their ancestors, they might be confused or disgusted.
In other words, this Age threatens to erase, from the world, everything that you believe is important.
This book is essentially an encyclopedia of predictions about the future. These predictions are derived using mainstream social science, and they are clear and concise.
This book is also an extremely *efficient* tour of psych research. Anyone who reads this book two or three times over would probably know as much, or more, as someone graduating with a Psych BA from a leading university. This is because Hanson cherry picks the highest-relevance items. It's also because, by stepping *outside* our Age, it is a little easier to see it for what it is (and, by comparing multiple Ages, one gets a sense of which features are Age-based [and, on what] and which are permanent).
The book is frustrating in that the factual predictions mostly take place in the next century. It's like watching someone hand in an exam, and waiting 100 years to see it get graded; no "payoff". And imagine, for a moment, that a hunter-gather sat down to write a book about the Next Era. Would he get it mostly right? Or, would it be so wrong, that reading it would be a waste of time? One can argue that we have more "data on eras" now, but, alternatively, the very power-laws these data seem to obey, could be used to argue precisely the opposite (ie, that the pre-X "data" aren't representative). The introduction notwithstanding, it is hard to see how the book's ideas affect anyone or anything in our reality. It's hard to get invested.
Correspondingly, my favorite section, "Dreamtime" had a higher (data & logic)/predictions ratio. It had nothing to do with EMs specifically, instead, Dreamtime simply reminded us of our place in the history of mankind. And it suggests that, of all the decisions that ever were made or will be made by anyone, only those of our Era will really matter. It's flattering and sobering, overwhelming and motivating. (And it is in the free Amazon preview section.)
I'm happy with my choice of Favorite Section, because I think a focus on "whether or not Hanson's EM Era actually arrives" is sorta missing the point. Instead, the point is that we should raise our game -- predictions about the future should be of approximately *this level* of breadth, detail, effort, and empirical corroboration.