Some decent information in here, but most of it is common sense. The deceptive title doesn't help matters, either. "88 Songwriting Wrongs" implies 88 specific items to help your songwriting, but you don't get 88, unless you consider items such as "Don't Send Songs By Certified Mail" or "Don't Send Songs To A Company Without A Specific Person's Name" as invaluable songwriting tips. (Yes, those are 2 of your 88 songwriting wrongs.)
When the authors do address specific songwriting mistakes, they do provide some good information, but there is a definite "The more you know about music theory, the worse you're going to do as a songwriter" attitude...there's a definite bias against formal music training, as if the authors feel the need to defend their own lack of training, and attack it as a negative quality in the songwriting world. (Tip #28 is where they really lose all credibility.) It would be one thing if this was Lennon/McCartney writing this book, or Taupin/Elton John...but the authors themselves have only a couple of minor songwriting credits themselves (one for Patty LaBelle, of which they remind you about on every other page, seemingly.)
The book is not a total waste, but it's certainly not the be-all and end-all in songwriting aides. You'll learn more about songwriting by studying the actual masters than by reading this book.