This book brings welcome attention to the neglected field of personal, general-purpose manufacturing. He argues that the technology is at roughly the stage that computing was when minicomputers were the leading edge, is good enough to tell us something about how full-fledged assemblers as envisioned by Drexler will be used, and that the main obstacle to people using it to build what they want is ignorance of what can be accomplished.
The book presents interesting examples of people building things that most would assume were beyond their ability. But he does not do a good job of explaining what can and can't be accomplished. Too much of the book sounds like a fund-raising appeal for a charity, describing a needy person who was helped rather than focusing on the technology or design process. He is rather thoughtless about choosing what technical details to provide, giving examples of assembly language (something widely known, and hard enough to use that most of his target users will be deterred from making designs which need it), but when he describes novel ideas such as "printing" a kit that can be assembled into a house he is too cryptic for me to guess whether that method would improve on standard methods.
I've tried thinking of things I might want to build, and I'm usually no closer to guessing whether it's feasible than before I read the book. For example, it would be nice if I could make a prototype of a seastead several feet in diameter, but none of the examples the book gives appear to involve methods which could make sturdy cylinders or hemispheres that large.
The index leaves much to be desired - minicomputers are indexed under computers, and open source is indexed under software, when I expected to find them under m and o.
And despite the lip service he pays to open source software, the CAM software he wrote comes with a vague license that doesn't meet the standard definition of open source.