I've been clinging to the last version of Xcode 3 for months now, as every time I launch Xcode 4, I end up frustrated and unable to decipher what the designers had in mind when they created this beast (Really, Apple? That aquarius-looking squiggly icon is supposed to denote "help" now? REALLY??? ). Xcode is arguably cryptic now, with functionality hidden behind meaningless symbols, gestures and key combinations, but this book helps the beginner to intermediate Xcode user figure out just where to find the info they're seeking.
Better yet, Wentk's book has actually helped me to uncover many of the hidden gems within Xcode 4, and I'm actually starting to enjoy using it now. Indeed, Xcode 4 is powerful and useful, and thanks to this book, I'm beginning to take advantage of its more advanced features, rather than just trying to figure out how to do what I could previously in Xcode 3.
This is the book that should come with every copy of Xcode 4.