It is difficult to review a 57 page book attempting to highlight the main points of a philosophical school, let alone the school's claims to ethics; however, I think Dr. Mary Warnock does an admirable job. This text very briefly covers Kierkegaard and Heiddiger and then launches into ~30 pages on Sartre's works. Warnock outlines their philosophies hand-in-hand with authorial contradictions and incompatibilities. I think the chapter on Sartre could be helpful to people who are (a) interested in getting to learn about Sartre or (b) people who are refreshing their memory of his work.
I think she hits the nail on the head with their major tenents, namely that one must break through the illusion of determinism for themselves in order to know they have free-will (choice in all situations). We are "nothing" at the core, empty and without essence, but we become (or are Being) through our purposeful engagement with the world by distinguishing (to know what is 'not' you). Thus, their is the contradiction of how to be ethical in your struggle against others if your actions should be inherently both ethical for you and all others: "All we know is that morality consists in the attempt to isolate oneself, to escape the influence of one's environment, and heroically to take full responsibility for what it is that one does" (49).
She ends by noting that Existential Philosophy is less characterized by tenets (it's general rule would be to avoid general rules) and more by "mood". With this point, I certainly agree, although I wish she spent more time excavating what she meant by this, because I think it would make a far more fruitful text. To me, this "mood" is properly characterized by Tennessee William's in his introduction of Carson McCullers' "Reflections in a Golden Eye," where he writes that Existentialism and the Gothic school have a particular similarity in the dread of living and having to be with others, a dread, which perhaps all people have to some degree or another. Is this universal dread of living one we all have? A question Camus tries to deal with in "The Myth of Sisyphus".
Overall, this text was a nice reminder of Sartre's projects and encouraged me to kick it with Kierkegaard (and feel confident with leaving Heiddegger in his Nazi grave) to bust down some illusions. However, I was left haunted with a question: what are the conditions of possibility that allow for people to theorize the possibility of a pure isolation from one's environment?