I've been trying to learn objective C and iOS programming with 3 books before this one, and I can finally say that I'm learning!
I come from C programming and some other minors languages and needed some deep base to understand how objective C works (which is what, at the end, will guide you thru programming) and the whole first part of this book is all about that: theory and understanding what is everything you see when you look into the code. All the previous books I've used failed on that and so they turned out to be useless for learning (at least I can use them now that I understand what I'm reading).
I think I've learnt a good lesson related to programming books: Never trust a book that starts right writing code unless you already know that language! Early 'Hello World' examples are totally useless since you find yourself writing a bunch of code you don't know what the heck its meaning is and is easy to get discorauged.
Can't stop recommending it, I've truly learnt how objective C works and, if you have a background as mine (at least previous C knowledge), this IS the book for you!