It's a hard-sci-fi story about how various societies, human and alien, attempt to assert control & hegemony over centuries of time (in many ways thinking of this as a distributed systems and code documentation problem!), and how critical and impactful the role of language translation is in helping people to understand foreign ways of thinking. At the novel's core is a question very akin to that of philosophical antipositivism : is it possible (or optimal for your society) to appreciate and emphasize with people wholly different from oneself, without interpreting their thoughts and cultures in language and description that's familiar to oneself, even if this is more art than science? There's a meta-narrative to this as well about how the reader should interpret the book with that question in mind, though to say anything more would delve into spoilers. And lest you think it's just philosophical deepness, it's also an action-packed page-turner with memorable characters despite its huge temporal scope.
While technically it's a prequel, it works entirely standalone, and is arguably best read first without knowing character details from its publication-time predecessor. Content warnings for mind control and assault (though they're handled thoughtfully IMO). Highly, highly recommend.