I purchased this after reading "Interrogations" by the same author - 'Road to War' is even better. Chapter by chapter it deals with the years running up to the outbreak of war from the perspective of the major combatant nations. What makes it stand out, in my opinion, is the fact that it is careful to place the outlook and decisions taken by countries in the context of what was known and believed at the time, i.e. without hindsight.
I found the chapter about Japan particularly interesting as although many people are familiar with European politics of the period, I previously knew very little of pre-war Japanese foreign policy and objectives.
I hope that "The Dictators" is as good.