This novel belongs aware of what is called the Hard SF: the goal is not so much the construction of history a pretext to a profusion of decorations, ideas and concepts. Noo novels could be compared as The Cycle of Non-AE Van Vogt Å or Hyperion by Dan Simmons. Clearly, we face a work that divided: either you love noo for its wealth of ideas and imagination in power or you'll hate it for its lack of consistency and construction. So it is a difficult to access novel, very different from other author that were much more affordable.
I put it a 5, but be aware that this novel does not compromise: you put him 5 or 1, but probably not in between!