Most of the book seems to be a set of step-by-step instructions about how to build the tutorial applications. Given the fact that this is "the" book to read when learning Cocoa, I would have liked to see more high-level information about the intent and design of Cocoa, callbacks, delegates, etc. I think the old Simson Garfinkel book on NextStep was better in this regard. The coverage of core data seems sparse and doesn't explain much about how it all works together. However, the book covers most of the topics one would need to know to get started with Cocoa.