The great thing about Pirsig's writing is that he takes apart and analyzes many beliefs that we take for granted in our every day lives. Then he resassembles them into a logical mapping that literally provides an explanation for everything, from the behavior of cells, bacteria, animals, trees, humans, societies.
Granted, the structure of the 'story' makes it such that it is more of a doctrine on morals and values rather than a page-turning novel. But that is what makes it great. We don't have to put up with unnecessary story fluff if it were a true novel, and we also don't have to deal with dry philosophical incantations with equations and symbols etc.
This book will only really be enjoyed by those who liked the first book for its philosphical analysis, because he picks up the discussion and takes it many steps further. For those of us interested in understanding our lives and our behaviors, of why we do what we do, how we got to where we are today, and what it is each of us individually and collectively value, he offers some very amazing and compelling arguments. And he backs each of his theories up with quite rigorous logical explanations. This is one of the main reasons I enjoy his work; he doesn't just throw something esoteric idea out there and wait for someone to prove him wrong; he follows every argument up with logical analysis.
Bottom line, if you are into the philosophy of it, you will come out of each chapter of this book with a different outlook on your everyday life. You will see things in a different light, and that is what makes this book great for me. There are very few other books out there that successfully do this.