This Great Courses lecture series is more challenging and requires greater concentration and effort than most of the Great Courses - and certainly more than your average audio book. If you are interested in the subject matter - I should say committed to delving into it - then it is worth your while. For me, that meant re listening to portions (even entire lectures), and reviewing the course guide in some detail. Not for the sunshine listener or the fair weather learner. I give it five stars.
( )