This series of lectures sheds light on the major contributors to Economic thought since Plato and Aristotle. Since the book is made up of transcripts of his lectures, he doesn't manage to cover the figures or the ideas in depth. However he does manage to give some guidelines as to what you should read if you want to be well informed on the history of Economic thought.
I did not find the language in it frustrating, it just made the book seem like a personal lecture with Robbins (minus the questions) which added to my enjoyment. He stops at Fisher, so if you were hoping for ideas and icons after that, you will be disappointed.
The book is split into five sections. The first deals with those philosophers that preceded the formal study of economics; Plato, Aristotle, Aquinas etc... Very interesting stuff, especially if you aren't familiar with the relationship between the ancients and economics.
The second to the fourth sections deal with famous economists, from Adam Smith to Karl Marx. His treatment of Marx is brief so don't expect anything more than a few pages. While he goes into some length about Adam Smith and the other classical economists.
Finally he lectures on Jevons, Menger and others of the "Marginal Revolution", ending his series of lectures with Fisher.
A good read, I would recommend it to undergraduates in Economics or any one else who is interested in the history of economic ideas.