Prof. Berridge's book is one of the most respected introductory books on Diplomacy, used from faculties of International Studies until introductory classes in Ministries of Foreign Affairs. The reason is simple: this book provides a brief and concise introduction regarding diplomacy, both in theory and practice. This book provides explanations regarding the origins of MFA, process of diplomacy, and the actors in diplomacy (including the diplomatic and consular mission).
There are some minor differences between this edition and the previous one (in which I have read both). Both are useful and complete each other. My biggest concern, however, is that sometimes the terms used in this book are rather difficult to understand for complete beginners or novice that have no previous backgrounds whatsoever regarding diplomacy. There are lacks of explicit definitions of the terms which demand readers to intensively read sentence by sentence to completely understand the concepts used.
This book provides some interesting examples in cases of diplomacy. Among the most interesting is clearly Reagan-Thatcher's 'telephone diplomacy,' which should be a very good story to make the point clear regarding the importance of the concepts.
To conclude, this is a very good introductory book. For readers that have no background whatsoever of diplomacy, you may want to read more intensively to understand the concepts, yet this book will surely provide you with great insights of diplomacy in our modern world.