Imagine an alternate history in which the cold war hadn't ended in 1989 and had instead continued to intensify. And to add fuel to the fire a mysterious object arrived in our solar system from who knows where that America gets to first and controls access to. If the Soviets believed the Americans were learning secrets that would give them an edge, tensions might escalate out of hand. But it isn't giving the Americans a technological edge, only offers confounding mysteries and a devestating vision of their future that they seem powerless to avoid.
This book, paradoxically, seemed both too long and too short. The overall story arc should either have been compressed down to a novel half the length or else fleshed out over two or three volumes. The sheer number of characters, minor story arcs, and mind boggling concepts explored was too much for a single book. Many of which could have been stripped out of the overall story without losing anything particularly important. On the other hand, more time could have been allowed to develop the many characters and their own story lines, the esoteric concepts more carefully explored if it was spread out over several books. Thus, it might be said, it falls between two stools. In particular, the last hundred pages or so was devoid of narrative tension as the story trundled to what seemed it's innevitable conclusion.
Another problem I had was visualising everything as it was described. I don't know if it was the author's use of words that made it difficult for me or if it was the sheer amount and complexity of strange environments, technologies and geometries presented to the reader to get their head around. Perhaps some maps, schematic diagrams and a glossary of characters might have been useful for reference.
That said, this was a visionary, ambitious work of SF that was crammed full of ideas which is precisely what SF should be doing. With a bit better writing and editing, this might have fulfilled it's potential to be the masterpiece it was trying to be.