Rating: 

If you're looking for more indepth coverage of dojo itself (like dojo xhr) or the core dijit library that comes with dojo, or anything in the layout, data.store, or dojox libraries, this isn't for you.

However, with pretty good knowledge of all these things already, I definitely learned a lot more about the dijit building process and appreciate the insight it gave me as it probably saves me some hours banging my head on my desk in the future.