Just bought the book; I’m about halfway through and have skimmed the rest.
There are two major omissions for me (in addition to a major rewrite of Chapter 2).
Many-to-many relationships only receive cursory mention on page 46 (in a discussion of the use of NSPopUpButtons). As such, the book only seems to act as a guide for the most basic of data models. The book stresses that one shouldn’t approach Core Data with the mindset of a relational database designer, so does that mean that there is a better way of modeling many-to-many in Core Data than just using “join models” connected by one-to-many relationships?
The contents page should stress that the iPhone chapter doesn’t discuss native use of Core Data but rather suggests a method for accessing a Core Data store using SQLite’s C API, with the assumption that Apple doesn’t change how it implements the SQLite back end. Even if the book is to be published before the NDA is lifted on the new iPhone OS, I’d have appreciated discussions throughout the text on why particular approaches might not be best suited to the iPhone given memory/speed restrictions even if one doesn’t go into detail on, say, what backing stores are available under 3.0. The sidebar on page 181 alone isn’t good enough.
Anyway, my initial feelings is that the book still needs a major revision to reach the quality one expects from The Pragmatic Bookshelf.