What's so special in this book. It is a book after all !. Anyway, I would think one would take the certification exam because one would want to learn / study to a greater depth the EJB 2.0 framework.
This could be done by a couple of readings of the spec, and some of the sample questions floating around isn't it? I mean that's what I did for
SCJP and the SCWCD and am on track for the SCBCD too.
Why all the hoopla about a book ? Anyway that book is going to no doubt explain the EJB2.0 spec albeit in a more detailed and expository manner.
I think people are tending towards reading all the sample questions and their answers rather than reading the spec...