Note: moving up due to a new comment
I have not yet received my copy but this should be wroth reading. It would be interesting to see whether a successful "very short" introduction can be written of Habermas' work.
Habermas: A Very Short Introduction
by James Gordon Finlayson
Here is a description of the book from OUP
"Provides a completely up to date and much-needed entry into the long and forbiddingly technical works of the most influential German philosopher alive today
Covers Habermas's influence on a wide variety of fields, including philosophy, political and social theory, cultural studies, sociology, and literary studies
Explains how Habermas's ideas are applied to present day social and political situations.
Unlike other writings on Habermas, this explains his intellectual framework and technical vocabulary rather than simply adopting it
This book gives a clear and readable overview of the philosophical work of Jürgen Habermas, the most influential German philosopher alive today, who has commented widely on subjects such as Marxism, the importance and effectiveness of communication, the reunification of Germany, and the European Union. Gordon Finlayson provides readers with a clear and readable overview of Habermas's forbiddingly complex philosophy using concrete examples and accessible language. He then goes on to analyse both the theoretical underpinnings of Habermas's social theory, and its more concrete applications in the fields of ethics, politics, and law; and concludes with an examination how Habermas's social and political theory informs his writing on contemporary, political, and social problems."
Preface: Who is Jürgen Habermas
1 Habermas and Frankfurt School Critical Theory
2 Habermas's New Approach to Social Theory
3 The Pragmatic Meaning Programme
4 The Programme of Social Theory
5 Habermas's Theory of Modernity
6 Discourse Ethics I: The Discourse Theory of Morality
7 Discourse Ethics II: Ethical Discourse and the Political Turn
8 Politics, Democracy, and Law
9 Politics Beyond The Bounds Of The Nation Alone