It's a harsh review. I'm going to step back and say some things about why it came out this way.
In retrospect, being a reviewer rather than just an ordinary reader made reading the book an especially painful experience. The book is very unclear, often with very different directions in which each bit of unclarity could be resolved. If there are 2 ways to read each unclear bit, and n unclear bits, you end up with 2n possible interpretations. (A lot of the unclear bits admit of many more than two possible interpretations, so really it's more.) Trying to live up to your obligations of charity as a reviewer and figure out which of this huge array of different interpretations is the best one is exhausting. An ordinary reader can just shrug, say it's unclear, remember the bits he liked, and forget the rest. But a reviewer has to correctly describe the view to everybody.
Usually things wouldn't be this bad. The organization of the book, perhaps, would enable one to slice down 2n to a manageable number, perhaps by isolating separate elements of the position. But the book is very disorganized. As far as I can tell, the clearest expressions of the positive view are scattered throughout middle parts of late chapters.
It wouldn't be so bad either if the differing interpretations had substantial and distinctive virtues. If you're a connoisseur of philosophical positions, which is a good thing to be in our profession, you might enjoy savoring each one. Instead, I spent hours and hours figuring out which of a large range of yucky views I had to attribute to Pippin. It was a miserable, frustrating experience.
I met Pippin at a conference a few months ago. He's a nice man, and he was nice to me and one of my graduate students. I think of him without any negative emotion, and I don't want my review to cause him anguish. (I don't expect it will -- I'm sure he's doing well enough for himself to shrug off a harsh review written by some guy on the other side of the world).
But insofar as this makes any sense, I'm angry and resentful towards his book for the misery it inflicted on me. As I wrote I wanted to avenge myself against it, and rescue readers from it, by making its faults clear so it would be avoided by all and honored by none. If there are points in the review where you're wondering what emotion drove me to write as I did -- well, that's the feeling.