This book does the intellectual equivalent of picking you up by the lapels and shaking you. The style is simple (though not simplistic) and straightforward. But it is also ruthlessly uncompromising. The book is littered with instances where Bonhoeffer points out the thinking of the person who wants to make excuses and worm their way out of 100% commitment. In those instances, I read my own words and thoughts coming back at me.
This was not merely an academic treatise. It is a call to action; to a life of devotion. Bonhoeffer's life and death bear the hallmarks of someone who lived out their writings in complete obedience to Christ. This is not to be read lightly, or glossed over. Read it and prepare to have your life changed.