I have long been a devotee of the OUP's Short Introduction series and when I wanted to buy an introduction to existentialism I searched there first, but was warned off by the reviews. Instead, by the same process, I ordered this title and I am really glad that I did. Wartenberg gives us a brilliant introduction to the subject. I had very little background knowledge of philosophy and even less knowledge of existentialism, but I was hungry to learn. Starting from first principles the author introduces us to the main issues of identity, individuality and self-consciousness. He deals with awareness of, and interaction with, others and the issues generated by free choice, especially in important moral issues such as racism. He explains the technical words that are unavoidable and I personally think the book is much enhanced by the short biographies and summaries printed in text boxes throughout the book. They deal with individual philosophers and their theories, so in a few words we can gain an insight into Kant say, or Sartre. Wartenberg makes no bones about being a supporter of the existentialist world-view. He is fully committed to it, but not in a way that obscures the truth or muddies the discussion; itself an accomplishment.
In short if you, like me, want to begin an exploration of this subject, one which has undoubtedly moulded our world, then this really is an excellent place to start.