Well, IMHO, there is only one book for this : RMH
I really enjoyed reading it, it reads smoothly, is very complete, pays a lot of attention to the BP and has lots of examples to illustrate the matter.
It is certainly one of the better books I have seen/read !
I also have the SUN book (
j2ee platform web services), it is worthless in terms for the exam. Even in general terms, I do not like it.
If you read the blue prints and some architectural considerations you gain more.
IMHO, the best approach for the exam, and to improve your skills (which is more important than the exam) is to start reading RMH.
I do agree that besides the RMH you need something more focused on the exam too. For this the MZ notes are perfect. Not that the RMH doesn't cover it, but you are never sure that what you read is an exam objective.
So, after RMH you read the notes, and for each objective you use the RMH to clarify/re-read it so you are sure you remember/understand all the important points for the exam. This way you have all the knowledge/understanding and as a bonus you are prepared for the exam as well. After that, you do some mocks to fine tune you exam preparation and to dig up some points that you do not completely understand.
If you find the RMH book to complicated, then you are either not qualified for this matter or you do not have enough experience to begin with this.
BTW; there is no HF book for this (thank god) I got the HF book for the SCBCD, to be honest I threw it away. I kept with the spec and the free mastering EJB2 (I did use the mock questions from HF however....)