I flipped through this book while at the bookstore. I see more and more books these days following the Q/A format. p20 is right, you do learn more efficiently with this format. I didn't buy it. I'm trying really hard to limit my list of review books for Step 1. My desk is already cluttered with various Step 1 books and Qbooks.
It's hard for a new book to break into an already saturated market, much like the one for medical review books. If Deja's book is really good, it'll take at least another 3-5 years before it becomes on the list of "must haves" for Step 1. If they're smart, they'll publish an updated version by then. Ok, enough rambling...