Short Review: The best of the three full biographies of Bonhoeffer I have read. If you have not read a Bonhoeffer bio, this is where to start. If you have read a recent Bonhoeffer bio Marsh adds a few things. First is is well written and avoids the chunkiness that some of the translated bios of Bonhoeffer have and the strange allusions that Metaxas uses.
Second, it spends a good bit of time on Bonhoeffer's childhood and places his privilege as both a positive (allowing him freedom to learn and think and travel) and negative (he was clearly spoiled.)
Third, Marsh does a good job showing how the two US trips helped to shape Bonhoeffer's theology. This is not so much about America being great (Bonhoeffer was really not all that impressed with the US as a whole) but allowing Bonhoeffer to see the African American experience and how faith could exist and thrive under oppression. Bonhoeffer was a great theologian prior to that trip, but the original US trip refocused his whole theological structure.
Fourth and related, Marsh does a better job illustrating Bonhoeffer's theology and how it changed over time.
My full review is on my blog at http://bookwi.se/strange-glory-a-life-of-dietrich-bonhoeffer-by-charles-march/