This book is outstanding. It provided just the right balance of a fast pace but not too fast as to be overwhelming. It is a prerequisite for any other iOS development book, unless perhaps if you are an experienced developer of Mac apps.
It covers Xcode 4, which is good for anyone starting out (why start out with an already outdated version of Xcode?). If you don't yet have Xcode 4, you will need to either pay $5 in the Mac App Store (prepare for a several hour long download) or pay the $99 annual developer program fee. I found Xcode 4 to be worth the upgrade price versus the free Xcode 3.
The book is extremely well written, assumes little to no prior C knowledge (although prior development experience will no doubt help), and explains basic concepts. I appreciated that it sometimes took "the long way" in example code, in order to have more readable code, rather than resorting to abbreviated shortcut code that can be much harder to read.
Even though the book is focused on Objective-C, it has a nice small section at the end that covers iOS development and walks you through a basic iPhone app: a fractions calculator. However, if you already have expertise with Objective-C and are just wanting to learn iOS, then this book might not be the best for you. This is best as the first book an iOS developer reads, and then additional books focused just on iOS would be the logical next steps after this book. But reading an iOS book without first having the understanding of Objective-C will likely set you up for failure.
While the book is excellent, the Kindle edition is a bit difficult when reading code samples. Also, some tables were completely unreadable on my 2nd generation Kindle. What I had to frequently do was fire up the Kindle iPad app (or the Kindle Mac app would work, too) in order to read the sample code and tables that were too small on the Kindle. This worked well. I read about 80% of the book on the 2nd generation Kindle, and the other 20% on an iPad 2 (using Kindle app). It actually works nicely to prop up the iPad next to your Mac as you type in the sample code.
If you only have a small Kindle and no larger device to read the Kindle book on, you might prefer the print edition of this book.
I highly recommend this book.