To start with, it seems clear that they do not have a full grasp of the philosophical problems they are attempting to resolve - or if they do, they avoid going into the stickier points. This is not necessarily a reason to condemn the book; there are huge volumes of philosophy on this subject, and it would be futile to try and fit a quick resolution into one small volume already full of other facts. Nonetheless, they probably should have avoided the philosophical aspect entirely if all they were going to do is attack the mind/body problem in a way that arguably does nothing but shift the terms around a bit to produce the appearance of a resolution. There is essentially nothing new here, philosophically, and they certainly had more than enough interesting material for a book without attempting this.
A second thing that disappointed me is the lack of contrasting points of view. It seems unfair to ask an author to present a summary of theories which argue against his own, but in fact it's in the best interest of an author/scientist. What are the points of contention between theories, and what are the alternate explanations? This gives the author an ideal chance to explain why their theory is superior, what it has that the others lack... and in turn it gives the reader the chance to be convinced (or not) by the force of the argument, which is always more intellectually satisfying than being led by the nose.
Stylistically, also, it could have used a bit of revision. Long, complex sentences are fine (great, even) for something like Proust. When you populate those sentences - even if they're perfect grammatically - with large and generally unfamiliar scientific terms, it can be quite awkward. This happened just frequently enough to be a nuisance, as far as I was concerned.
So, apart from these criticisms, the subject material is still interesting. I would be inclined, however, to look for a more recent title by these authors (or others) on the subject. A lot can be discovered in a few years, and hopefully the experience they gained in writing this book will help them produce a work with a bit more polish.