I am a complete beginner when it comes to programming. I found the flippant style half amusing and half irritating but I guess it helped maintain my interest.
Most of the book is quite clear, but there are concepts which are not well explained. For example, if you are not familiar with Functions and Arguments, you're left wondering how exactly this all works and why all of a sudden a function call is using arguments with names different to those the function was initially declared with. It all becomes very confusing.
Contrast the examples in Javascript - Annotated Archives, (ISBN 0078823641) where each single line is carefully explained. Now I am not suggesting this is the right book to start trying to understand Javascript with, but the two together did it for me.
Vander Veer's basic problem is that she can't be bothered to fully explain; and this is not helped by examples which are just fragments. There comes a point when you need to explain the whole thing, in one go and not just make promises (and there are plenty of them) that you will explain later in the book. Are readers supposed to put pen to paper and keep a list of things which will be explained later? By the time later comes round, you've forgotten what it was the authro promised to explain 'later'. Even more disappointing, is when the author does not keep her promise and explain... especially because when she can be bothered, she is quite good.
If this is Javascript for Dummies I probably needed Javascript for Amoebas...