I read Bonhoeffer by Eric Metaxas about two months ago and it was FANTASTIC! A little dense in places since it's a biography of a very prolific, intense man during a very intense, complicated place and time (World War II Germany). Bonhoeffer's life was very inspiring and I highly recommend the book. I'm now planning to read some of Bonhoeffer's own work. Especially after reading excerpts like this one:
It is only the cynic who claims "to speak the truth" at all times and in all places to all men in the same way, but who, in fact, displays nothing but a lifeless image of the truth....He dons the halo of the fanatical devotee of truth who can make no allowance for human weaknesses; but, in fact, he is destroying the living truth between men. He wounds shame, desecrates mystery, breaks confidence, betrays the community in which he lives, and laughs arrogantly at the devastation he has wrought and at the human weakness which "cannot bear the truth."
~From Ethics by Dietrich Bonhoeffer