I'm a big fan of collections of essays, especially among professional philosophers where there are often a lot of views that hang together in interesting ways. These sorts of collections allow us to get a look from a few different angles at a variety of useful topics, instead of trying to be a unified account, which is often difficult and tedious.
Churchland covers a lot of ground in this book, and doesn't pull it off quite as elegantly as some of his other books, which I'm rather fond of, but he does give a number of difficult topics a good swing. The book primarily ties together Churchland's view of science [his scientific realism] with epistemology and philosophy of mind. The book follows a general psychology first model of epistemology, where the structure of mind is the primary force in informing a theory of justification. This makes for a pretty interesting read, and there are very few philosophers competent in the neurology and psychology to take this sort of approach; it does wind us up with a number of fairly radically different conclusions than other mainstream philosophers, and that should lead to some concern and some sense of a need for thorough analysis.
The book responds to a number of prominent critics, particular Bas van Fraassen and Jerry Fodor, and so it does require some familiarity with the source literature. This is a book that is written by a philosopher for other philosophers; it isn't trying hard to be accessible and so it won't wait for you if you're new to theoretical epistemology. Because van Fraassen and Fodor are both strongly situated philosophers, Paul wastes no time just jumping on the implications of their views, and if you're not familiar at least peripherally with where they are in the literature, those sections will be totally useless. That is less strongly true for Churchland's discussion of some other historical figures in philosophy. I don't recommend this book to folks who are new to the philosophical literature. It'll be frustration and unhelpful.
There are some parts of the commentary that are a little underdeveloped; the last chapter dealing with moral psychology feels lazy and rushed, and I found it unrewarding. There's something to be said about the role of the neurocomputational approach to philosophy of mind when it comes to moral psychology, but it isn't clear that Paul has done that lifting; it certainly isn't in this book. In that sense, the book really is about philosophy of science more than a general survey of how the philosophy of mind of Paul Churchland fits into his other philosophical views. Anyway, the book is well written, antagonistic where it needs to be, and will be useful for those who are trying to figure out how Churchland's theories about mind fit into epistemology and philosophy of science, especially in contrast to many of his critics.