This book is great. The author doesn't assume you're an expert in c or objective c, as I have no knowledge of neither; it was a great starting point. Everything is really well explained, and you can create some great applications when you finish the book, mostly by just combining what you're learned in multiple chapters - into one application. The book is really well laid out, there's no need to search through pages to find a screenshot. There's a screenshot corresponding to most of the stuff you do during the entire book - which makes it really difficult to get lost. There are a few errors, but very few, most of which are covered in the errata. You basically go from chapter one, which helps you to register for iOS development program, to chapter 24 which helps you to publish your application to the app store. I have never felt bored while reading this book. I have however found 1 chapter to be completely buggy; which I have skipped, and one which seems as if it was written by a different person, as it's so fast paced, that it doesn't really match the pace & the style of the previous chapters. But that still leaves plenty more chapters for you to go through.
Overall, I'd recommend this book to all beginners, if you have already done some iPhone programming, then you might find some stuff interesting/new, but you should really focus on the apple documentation. This book won't make you write the greatest apps, but it's an excellent starting point. I was and still am, really surprised by how good this book is. I hope there'll be more books like this one.
I have managed to complete the whole book using xcode 4, but the author uses xcode 3. You might need to do a bit of research as a few things have changed, but it's definitely possible.
UPDATE:
I have contacted the Author (John) about the issues I had, and he helped me out; so I got all examples working.