This is a very good one, some chapters are very impressive, for the number of approaches being described to solve the same requirements but also for the simplicity of the language. For example the chapters on object inheritance and prototype are great as well as the section on closures is probably the best description of Javascript closures I read.

Only a small section of the last chapter is pretty disappointing given that I am mostly a software designer, the design patterns section.
For example writing that a javascript object literal is like a singleton is just meaningless and misleading.
A design pattern is a (design) problem frame, not a label and not a description of a cloneable solution. The proposed solutions are probably the least important part of a pattern, identification criteria and problem frame are the most important.

For the rest the book is definitely one of the best core Javascript guides you can find. ( )