It seems the definition of hard science fiction is more elastic than I thought. This book, by Vernor Vinge is supposed to be hard sci-fi. What I got from it was more space operaish because there was little nuance - the good guys are good because they are good and the bad guys are bad because they are bad; there was also a love/hate relationship a la Mills and Boon, except without the hot makeup sex. Also, for a story purporting to be hard sci-fi, it assumed that beings originating from different planets could share the same spaces without modifications for gravity, air, differing reactions to stimuli and so on. This is not really a failing since it is normal for Star Trek and Star Wars. However, unlike Star Trek, it ignored the danger of adverse reactions from breathing on an alien planet without protective equipment, or eating alien food without testing. I thought this was rather sloppy since books do not have the restrictions of films. I suppose all this can be waved away with some deux ex machina explanations or even just dismissed as carping, and I agree. But, they are issues that detracted from the story, making it seem like pulp fiction. If it is really hard sci-fi, it lacks the cachet of stories like Clarke's Rendezvous with Rama or the wonderfully immersive and intelligent Mars Trilogy by Kim Stanley Robinson.
It seems the 2 most lauded concepts in the book were (1) the inverse correlation between proximity to large concentrations of matter and technological complexity; and (2) the group mind species on Tines World.
I did not think the first concept was particularly intriguing. Liu Cixin, in The Three Body Problem trilogy had a more interesting if less plausible method for allowing universe wide effects using god like technology.
However, the second concept, which raised questions about mind and identity was really interesting. I like books that make me want to reread others, and this made me determine to reread Ann Leckie's Ancillary Justice. That book, which I disliked because of a shoehorning of a gender agenda (which added nothing to the story) had an interesting and novel (to me) type of group or maybe compound mind. Before that book, the only instance I knew of was the Borg in Star Trek. The group minds in this book are the dominant species in Tines World. They are dog like creatures that become individuals only in a pack. A minimum of 3 and a maximum of 8 individuals communicate sort of telepathically and combine their minds to form one person. A pack larger than 8 becomes a mob. Packs can be fragmented and then fragments can combine with others to form a new person that is an amalgam of the 2 previous ones. These creatures were the most developed characters in the book I think. The book ended with the beginning of an alliance between them and humans. If not that I do not intend to read more of this author, I would have liked to know if subsequent books expanded on this relationship given how well we get along with dogs in reality.
This is a story interesting in parts. The part about the threat to humanity and their neighbors in their region of the galaxy, as well as the description of the galactic internet was meh. The bit about the low tech Tines World was better. There were multiple storylines that eventually converged, this was rather confusing. However, it seems to be the author's style because I have begun another of his books, it is a prequel to this one but written later.
The author is lauded as one of the greats of the genre. For me he isn't. I doubt I will buy any more of his work.