The question that most people want to be answered is if this is the book to replace the venerable Mac OS X Internals by Amit Singh. In my opinion it’s complementary with some good updates and interesting tips.
I wasn’t expecting to buy this book so soon due to some Twitter comments and to printing issues, with at least one chapter missing and replaced with another from a ASP.net book. A project I’m working at antecipated my waiting. I haven’t read the whole book yet but some six or seven chapters both from the introductory part and the more advanced one. The writing style and edition quality are good, which is a benefit from a single author. This contrasts for example with IOS Hacker’s Handbook, where the edition quality is poor and the writing styles so different (too many authors, not much edition work). There are printing errors here and there, with swapped outputs, messed up structures, some missprinted words. Nothing that puts in question the overall quality.
The main reason why I think it’s not a replacement to Singh’s book is that content feels short in many places. Some subjects are briefly introduced and then not developed. I would describe it as a good overall and updated (this is a very positive point!) introduction to Mac OS X internals. The iOS component is mostly brief references to differences or missing stuff (it’s a tough work here since its source is not published!). There is a lot less code and listings compared to Singh’s. One thing I like a lot are its diagrams and figures, simple and clear.
An update to Singh’s book is being done by Gwynne Raskind although the release date is probably late 2013. One must wait to see if the new version will take the number 1 spot. This one is a good addition to your library and if you are new to OS X internals it’s probably a good place to start and then buy Singh’s book if you want to go deeper. Congrats to Jonathan Levin, (good) book writing is not easy.