This book drives some folks nuts, but I understood that it was a first novel and read it as such. Ray Nayler has digested quite a lot of material on his subject (the octopus, of course) and a lot about everything else. His choice to have the quotes at the beginning of chapters be from books he made up is a tip for the experienced reader--you're going to get a novel that is pretty up front about being an exposition of the author's philosophy on whatever is covered. Nothing wrong with that, some really good authors (Octavia Butler, Isaac Asimov) have done it. I think it's even better when an author can make other non-fiction authors speak for them (I should have examples but I don't), but the quotes worked so I have no objections.
The characters in the story are not meant to be either sympathetic or not--they just are who they are. A recurring theme is that of people who are trapped by the larger forces at work on their issues. Eiko, a trafficked slave on an automated fishing boat, is the most obvious one. Some think this subplot is a digression, but I disagree--his story is meant to illustrate the depraved cruelty of the times and get you to anticipate the captivity of all of the other major characters. It's pretty easy to imagine instantiating something like this now. If we're lucky we'll read about it in a few years. If we're not lucky the story will be suppressed and we'll never know.So the evolution of octopus intelligence is the macguffin in the story, but it really reads more like a backdrop for the author's philosophical vision of the future. Pretty dark but that's where we are now. I think it is worth the read if you go in understanding the limitations.