While this book got into the suspenseful action more quickly than Peters's Amelia Peabody series usually do, the overall action was never made fully clear regarding what the villains were up to, why Ramses and David had the experiences they did, and who helped them and why. And on the flip side of developing the suspense quickly, it resolved everything way too quickly, leaving readers with a rather foggy understanding of how the derring-do action fit into the overall arc of the plot.
Characters weren't developed at all, really -- pretty static, as was much of the book overall. It seemed like a book that was written as an afterthought, rather than written as the characters grew in Peters's thinking.