Book is OK, but it touch so many aspects of js web applications, that its in place quite shallow.
But, it raise a good points that we should think when we do write code. I liked a way Eric structure it - easy to navigate, you can concentrate on topic and then do googling about it for further reading.
I didn't liked some of the examples that were using Erics own libs - he did a good job trying to explain how do they works, but I just don't get it why he was using them across this book, there are other tools that can be used for the same thing (which were not mentioned).
If you are a veteran, don't read it, but there are some good points in this book, and for newbies, they should make them think.