When you read an instructional book and continually wish you had another book to explain it, then the book has failed.
In common with other reviewers I found the information in this book to be well out of date. Usually in Dummies books they take a 'fill-in-the-blanks' approach to getting you started, the emphasis being on getting you to a working result as quickly as possible, and then explaining the theory later. This approach was never going to work with this topic because the Facebook platform changes week by week. The author acknowledges this; I've lost track of the number of times the author says "at the time of writing...". It would have been useful therefore for him to abandon the usual Dummies approach and give the reader some much needed theory: for example explaining the parts of the Facebook screen you can and can't change, building a top-down explanation of terms and concepts, etc. But no, the author presses ahead with page after page after page of screens and forms that look nothing like what you will actually see when you come to do it.
Rather than giving us a structured look at the Facebook platform, the author darts about, talking about javascript here, HTML there, a bit of PHP, then a tiny bit about authorisation, then back to the canvas, more javascript, a bit abouts tabs, then iFrames, more settings and a bit more javascript. He goes from talking about high level marketing concepts to low level detail about javascript variables and back again sometimes on the same page. There is no discernible structure. This lack of structure means you don't build a mental picture of how Facebook applications work and you also don't see a story of how an application is built step by step. In short, the author probably knows this subject inside out but has no skill at getting it across to others. The Dummies editor, if there was one for this book, should have spotted and corrected this serious shortcoming.
I've given up on it. I'll keep it for reference and give it 2 stars on the expectation that it might come in useful later on. On almost every page the author refers the reader to look at the latest content on Facebook's own developers website. Here's my suggestion: save yourself the cost of this book and go directly to the Facebook developer pages.
