I have a general question about this book, having struggled and second-guessed my way through every project so far I wonder if there is any point using xcode4 while trying to make my way through this book.
The downloaded Source code using xcode3 file structure works fine, but I don't learn anything from just letting that run...
Thanks for any help.

I've stopped using the book for now (I may go back to it once I am more advanced) but I disagree. I would recommend sticking to xcode 4. It is definitely confusing when you first start using it, but the more you use it, the more you'll become comfortable with it. If there is something I can't figure out, I google and usually find the answer that way.

The changes that have been made are for the better, such as being able to connect your code with IB much more easily, and I want to learn that stuff as I go as well, rather than doing things the old way. Just my opinion though.

I would recommend that you do the projects first in Xcode 3 and then redo them in Xcode 4, using the transition guide and, as needed, asking questions here. Understand the programming concepts without letting the IDE get in the way. Familiarity with Xcode 3 will make the move to Xcode 4 easier. You will know where things were, and when they are in a different place or done a different way it will stand out. In many cases you will probably find your way around without issues. I would suggest doing about 1/3 of the book in Xcode 3, then as you continue through it, restart from the beginning in Xcode 4. About 2/3 of the way through the book you will have a sense of how you are grasping the programming concepts, and the environment should also be more friendly. At that point Xcode 4 can probably become your main environment.

Bob