Contrary to what the title claims, this book is not for dummies. If you have absolutely no idea what you are doing when it comes to iOS Programming (like yours truly) then this book is not for you.
If, however, you have some idea of what you are doing (including a decent knowledge of Objective-C) then this book will probably be a very useful reference text for you. I would have given it three stars if it did not have "beginning" in the title, but since it did, I feel a bit lied to.