I've often seen Ember described as hard to learn, and having a steep learning curve. In my learning process I've also found that there were a few stumbling blocks but once I understood the core concepts behind these, I realized how productive one can be in Ember and how great it felt to work with the framework (it still does, by the way, even more so).
I wrote the book with the intention of explaining these core concepts in depth and to do so in a pragmatic way, through building an app in the book where we apply the learned concepts to extend and improve it. Judged by the very positive feedback, it seems like I've succeeded though I will not rest on my laurels. For one thing, I need to keep the book up-to-date with the latest Ember version so that the fast-changing (and ever improving) framework doesn't make the book's contents outdated.
Rock and Roll with Ember.js