This book provides a succinct account of the limits of knowledge about the circumstances behind the rapid Islamic expansion from Medina, including the Ridda Wars immediately after the death of the Prophet Muhammad (PBUH). What this book lacks in situational nuance it makes up for by bridging a gap between academic detail and a tone/level appropriate for the non-scholar.
For the scholar, it is very possible to trace Jandora's sources into the labyrinth of unknowable and indefinable half-truths that confound the early days of Islam, especially where those half-truths tend toward polemic, toward the glorification or slander of one or another faction or tribe upon whose chain of narration the extant sources depend (Waqidi's Maghazi, etc).
However, for the non-scholar, if looking for a book that invokes, rather than describes, life in Arabia at the moment of Islam's first flourishing, this is not the right book.
Jandora provides some interesting insights into military organization and the limits of what should be considered tactically and strategically possible at the time of the Islamic conquests. It is in that area where this book proves most valuable, debunking inflated or unrealistic claims of less martially-minded scholars.