I move from software technologies almost yearly, starting with PHP to ASP.NET and now starting iPhone development, so each year is basically another library of books I have to buy to teach myself the language. I've read a ridiculous amount of computer books, ranging from the terrible (super boring, dense) to the insultingly easy ones (that basically treat you like a 4th grader learning programming.)
This, thankfully, is a fantastic mix of being incredibly easy to pick up and read, and also super informative. As far as iPhone development goes, this will be my 4th introductory book I've picked up, trying to get a handle on developing for the platform. The other books all typically tend to throw you into immediately coding, and never really actually explain why you're doing what you're doing, or make sense of any of it. Yes, this book does start off with an example chapter that you basically just copy word for word, but that's mostly to get your feet wet before actually digging through all the details and building your foundation.
In the first 3-4 chapters of this book, I already feel like I have a complete grasp on subjects that I did not yet understand from the 3 previous books I've read. I sort of had an idea why I typed '*' in front of names, or what @property (retain) statements meant, but I never fully understood what I was doing--it was mostly just "well, I read it, so it must be the way to do it." Basically, the other books got me about 75-80% there, but this one is 100%. The last 20 I feel is the most important, because that's when you finally begin to understand the concepts of the language, which let you move onto the more complex stuff with confidence.
Another reason I feel this makes a great coding book is the layout of each page. I can't tell you how important it is to present all that text + code in a meaningful, organized way. I've read some books where they just hit you over the head with instructions, with almost no visual clues and with fragmented code samples. But the pages in this book have plenty of white space per page, have plenty of illustrations and each code sample is commented (an appropriate amount) to give you hints as you're typing code as to what you're doing.
Finally, and thank goodness for this, the first example in this book that you write is NOT a Hello, World app :)
In summation, if you're like me and have started to read a few books (or maybe you haven't, I wish I could have started with this one) and are looking for a way to really feel confident with iPhone core concepts, then pick this book up and give it a read. I can't wait to get started on the many project ideas I have!