This book is nightmarish, not the writing or the plot, but the content, a vision of the future as bleak as possible. A culture of immortals whose only goal is long term survival, and who don’t like change or rivals in any way. Aliens or deviant human societies get crushed, and even those who work for the Metastable Order can’t escape the cruel requirements of their jobs. There’s no escape, even if they try to flee by killing themselves, the technology of the Metastable Order just recreates them.
It’s a nightmare, but an extremely well done one at that. It’s one of the few books that imagines a galactic civilization without any form of FTL. The whole civilization remains coherent despite the fact that they are limited to the speed of light, and that may be the reason why they have become how they are, fearing any change as a threat to their civilization. A grim vision of the future that is hard to come by anywhere else.