On the bright side the text is well written, with few spelling errors. The text goes far beyond the scope of purely helping the reader to prepare for the exam. The exam questions are advanced and most are difficult to understand. Although Javascipt is clearly not a prerequisite for the exam, there are some tricky examples i.e. in forms, which could be used as a reference.
On the dark side, the text is sometimes not easy to understand. This is definitely no book for beginners, such as the one offered by the Head First series. The catalog of the errata page is quite long too, especially for the first prints.
All in all, the book which was published in 2005, is surely not a primer. It could also be used as a reference later in your career, but you might initially need a lower level text to read, before actually attempting to sit for the exam.