I began Konrad Hammann's Rudolf Bultmann: A Biography in late 2013 and finished yesterday. It has been a book that I've been reading on the side in my spare time. I must say that it is a fantastic and thorough book. It covers so much information ranging from stories about Bultmann's family to his academic works to controversies caused by his ideas to debates with colleagues and students and everything in-between. For anyone interested in this book let me recommend it. It is readable, but not superficial, and well worth your time—even if you take as much time as I did to read it!