This set of lectures, published for the first time in English, reflect the rigor of Heideggerian method of philosophy. Heidegger discusses the question of human freedom with reference to Kant's pure and practical reason. For Heidegger the essence of human freedom is the fundamental problem of philosophy because it can illuminate the whole through the part.
Heidegger also typically links his question to the 'leading question of philosophy', which permeates Heideggers oeuvre - that of being. After a brief investigation into the positive and negative concepts of freedom in Kant and concepts like causality etc., he explains why it is necessary to understand being to understand human freedom and launches a hermenuetic/etymological inquiry into the concept of being in Aristotle's metaphysics.
At this stage you begin to wonder, why Heidegger is taking you deeper and deeper into the question of being when you are reading the book in order to understand human freedom. But Heidegger rarely follows a line of argument aimlessly. By discussing being and causality, he connects back to Kant to show that there can be a double causation of being and humans are the only beings who can ascertain this causation through their consciousness, bringing human will and freedom back into the picture.
He then discusses the other concept of freedom in Kant, based on 'the categorical imperative' but here he falls a little weak, especially when he dismisses the contributions of Scheler and Hartmann towards a non-formal ethics, (although his grounds of dismissal remain valid in principle, they miss the critique of Scheler).
Yet, this book teaches you more than the essence of human freedom - it teaches you philosophy and the method and duty of philosophy, something which many contemporary philosophers easily forget.