This is a careful, immensely well-informed, and persuasively comprehensive examination of the domain of settlements in space.
Kind of spoiler alert (but not really): They are not optimistic, certainly not in the short- or even medium-term. What the book does is share the reasons for their stance. And while there is a certain accuracy to the term 'disillusionment' here, in that they started the project optimistic and wanted to provide a popular introduction to how it will all be achieved, the end result is not a 'downer'.
What the authors get across - I think implicitly, but they also take time at various points to be very explicit about it - is that they love the science. They enjoy not the power fantasies of "Wild West in Spaaaaaaace!!" but the complexity, intricacies and crazy dynamics of life, and just as importantly living; being human in space, and on other planets.
They point out that striking out for the Final Frontier is less a prospect of strapping on a space suit and marching, steely-eyed toward Star Trek, or even the Expanse, world conquering and infinite fame. It's a bit more like saying "I want to move to live and work in one of those toxic rare metal manufacturies in China. Maybe raise a family in the foundry there, if we can avoid dying of poisoning, asphyxiation, or radiation." Except the China thing is likely to be more pleasant.
What they suggest instead is more ambitious, more visionary, and ultimately a great deal more heroic too. Something that would really stretch what our species is capable of, require efforts to transform technology and social organisation. They see that as worthwhile and inspiring, and they aren't afraid of the hard work and long-term thinking it would require. (Or at least, they aren't afraid of signing other people up for it, let's be realistic here.)
It's a book that can change your perception of space, space settlement, and your relationship to the world around you. I really like the Weinersmiths. They seem like excellent people.
As a chaser to this excellent shot, I would recommend the entirely different
"How Infrastructure Works" from Deb Chachra. A different perspective on our relationship to the world, but one which makes very similar points about how deeply and fundamentally we are bound into our own world. bookwyrm.social/user/wildenstern/review/3831758/s/debchamastodonsocials-book-will-change-your-perspective-on-the-world-connect-you-to-roots-and-implications-you-werent-aware-of