While he makes several good points about the need for believer to be involved in the mission of sharing the Gospel, he makes some dangerous statements that only through the direct intervention of a believer can an unbeliever come to salvation.
Although this "update" is 40 years old, this book remains as relevant as ever. It touches on a number of issues relating to the lack of evangelism in the American Church. Although there is little here that I haven't already heard or read elsewhere, I still found this book very motivating as to personal evangelism. And the final section on the crucified life was really thought provoking. By all means, get a copy and read it!