I honestly love this book. From the framing narrative of a Void Engineer giving their history to a bunch of Reality Deviants (one of each of the major types, in fact) including the reveal at the end bringing the whole thing into question and giving rise to a major chunk of the Nephandic Infiltration metaplot for the Technocracy. It's really a modern Convention Book with a nuanced view of the Technocracy and one that clearly internally, at least, has them as the heroes.
It contains decent mechanics for Voidships, and seems to be the place where the exploration of the galaxy is farthest along (at least, I don't believe later books suggest that they've gotten as far as this one claims they have.) In fact, if there's a flaw, it's because them having significant extrasolar exploration is a bit beyond belief, though they justify it by Kepler and Einstein having worked together to find a hole in Relativity (Newton, also a Void Engineer apparently, had been killed a few decades earlier).
Overall, it's a very good book, with lots of useful procedures and devices, a solid narrative, and it makes it clear that Void Engineers are more complex antagonists who are more tolerant of Earthly relatiy deviants, simply because out in teh void, anything vaguely human is more friend than the natives are.