Brilliant book. I enjoyed reading it very much. There was a lot of new information for me in it. 
 The most important shortcoming of this book is answering why peoples within Eurasia ended up so technologically different. There is a small section of the book dedicated to answering that but It needs a whole lot more than that. As a middle eastern, my version of Yali's question is "how come Europe dominated the world if middle east is where civilization was born" and this book doesn't have a clear answer for that.