I agree that the book is may be out dated on its current scholarship (Heidegger's Being and Time
had yet to be translated into English when it was written), but it is still a wonderful introductory survey. That is funny that you mention Kaufmann's book. Irrational Man
and Kaufmann's books were the required reading for the existentialism class I took a couple of semesters back. The one thing that Kaufmann's book does provide is exerpts from primary sources. Of course, not all of the selections are representational of the work they are derived from, considering they are taken a little out of context, but the book serves a purpose. A poor attempt at a collection of original sources, but an attempt nonetheless. Unfortunately, there are not many other alternatives.