While the book does a great job of collecting the views of the major current philosophers on this topic, it didn't address possibly what to me is the most interesting paper to date on this subject. I speak of the 1998 paper by V. S. Ramachandran and William Hirstein--"Three Laws of Qualia: What Neurology Tells Us about the Biological Functions of Consciousness, Qualia and the Self."
In this paper the authors pose a convincing explanation for the knowledge problem. They argue that the epistemological barrier is only apparent, is essentially one of language, and the experience itself is lost in the translation. They imply that Mary never had all the physical facts as her brain never went into that configuration of neurons that mean the person is experiencing or seeing the color red, and that had Mary had available to her a "neuron bridge" through which this purely physical configuration was made available to her, only then could we reasonable say she had all the physical facts known to her. In other words, an important physical fact of the color red for a human includes the way the neurons in our brain configure on seeing red.
The omission of this paper and also of any discussion of this paper, which was published in a very well known journal, about six years before the date of publication of this book, is a surprising, puzzling, and serious omission. For this reason I only give this book three stars--many of the papers are rendered moot in my opinion as they fail to account for the very understandable, commonsense concept above, proposed by Ramachandran and Hisrstein. All the papers in the volume are authored exclusively by philosophers and in this day and age, this kind of silofication on a topic, particularly in the cognitive sciences, should be a thing of the past.