Once again, Sawyer manages to put a whole lot of interesting material into the package of (by today's standards) a modest sized novel. In this book, he takes on the nature of consciousness and the meaning of personhood, and as he's done in past books, he presents some ideas that I don't necessarily agree with, but he presents them cogently enough to make for very interesting thinking.
I will rule that I'm not violating my no-spoilers rule to say that the vehicle for this investigation is a company that has perfected a commercial process for downloading a human mind into a robot body. (It's not a spoiler because you've probably already figured this much out from the title and the cover picture.) The commercial success of the company, of course, is based on the robot being able to take the place of the original person in society, and of course this leads to conflicts which form the framework for the plot. Sawyer manages good enough techno-handwaving to make the basic concept reasonably believable, even to me (and I'm rather heavily biased against believing the idea; the idea that a computer can become a person conflicts with my core beliefs about reality). Along the way, he manages to present compelling arguments for both sides (of the question of whether an 'upload' is the same person), and also to speculate very reasonably on how society will react (which is a very different matter, in a question of ethics, than what's right). There's also some interesting exploration of what it might be like to be a robot, and a convincing portrayal of some mental problems that I find it a bit hard to handle sympathetically.
There's another aspect of the story which touches on the ineffable nature of consciousness and how it fits into physical reality. I started to write about this complaining that it was an inconsistency, but as I thought about it, I realized that he isn't actually changing the rules in the middle of the book the way it struck me; instead, he's hinting at something quite interesting about consciousness without coming out and saying it explicitly. I think there is a minor plot hole here -- I think Sawyer is either vastly underestimating the amount of data that it takes to represent the physical part of a person or just failing to consider some implcations of that amount of data. But I think I can forgive it.
This is a highly thought-provoking novel, and a good story as well. The ethical considerations are relevant to our times; while I was reading the book, I heard an interview with a so-called futurologist on the radio who was predicting human consciousness moving into machines in the next few decades in an entirely serious way, although by a very different path, and this guy brought up some of the same issues that Mindscan does. As a society, we need to get our heads around these issues, both specifically about machine consciousness (because something of the sort may actually be possible, and if it is, we probably will see it within our lifetimes), and the wider issue of personhood (about which, as a society, we're seriously messed up). You need to read this book, and you're likely to like it too. 9 out of 10.