I speak Chinese pretty well and wanted to shore up my slang, plus it's just kind of fun to know how to cuss people out. This book was a help in that regard. It's a pretty exhaustive list, it's well categorized, and there's good notes explaining when each slang is used. I've learned a lot of new words, and more importantly, I found out that I was sometimes using an uncommon or scientific word, instead of the proper slang.
So mostly I'm positive about this book, and I recommend it highly. But I'll concentrate on the negatives, just because it's difficult to judge a slang book, and to let other buyers know what they're getting into. My first complaint is that while the book is largely accurate, it isn't entirely. Maybe a couple percent of them are off. I don't think it's just the vagaries of slang or regional differences, because I asked several people here in Shanghai about them, and they all told me "no way." Anyway, it's worth double checking favorite terms.
Secondly, this is (for the most part) Beijing slang. OK a lot of the vocabulary is universal, and that's particularly true to the (really excellent) Internet slang section. On the other hand, there's a lot of words that I don't think most people would say in Shanghai. For a non-native speaker to use many of these words would be bizarre. I wonder, do people in Beijing swear a lot more? Even though she addresses the issue in the introduction, I think the author drastically overestimates how often and how deeply people swear. And a whole lot of the insults would instantly lead to a fight. Oh yeah, and the book is missing common Mandarin slang words that are used in Shanghai.
Third, it's CRAZY that this book has pronunciation guides for people who don't even know pinyin. If you don't speak Chinese pretty well already, don't try this book. You'll just get in trouble. Maybe it can be read for the cultural notes, but personally I found the cultural notes could sometimes get a little cartoony, particularly in the introduction, about the marijuana smoking pro-democracy rock singers...
Finally, I wish the book had better notes or division about which slangs were common, and which ones weren't. The most common words are often pointed out, but not always. And there's a whole lot of pages given to slangs that are hopelessly obscure. There is a "top 25" list at the end of the book, it could have used a similar section at the end of every chapter.