This book is great! I can put it no simpler than that!
I have read a lot of EJB text and this book is engaging, technically rich and to the point. The second edition has been updated for the EJB 2.0 spec and has had, as far as I can tell, a good re-organisation.
If you need a quick guide to a particular topic, then you can read that section. Alternatively I have been drawn to read it cover to cover. You also definitely get the impression that Ed Roman is a developer's developer. I can imagine discussing design ideas with him at the office!
If you want to read a great EJB book, then buy it!!