"Between Wittenberg and Geneva" is meant to be a conversation regarding Lutheran and Reformed theologies. First, the authors chosen for this book were, I believe, great choices as they represent fairly accurately the conservation of historical/confessional Lutheran and Reformed theologies, the topic of which I will get more into in a second.
While the book was helpful in comparing these two systems of theology, I did not feel that the book was much of a "conversation." If anything, it seemed like more of a introduction to these systems than a conversation between the two. Eight topics are covered from "Scripture and Interpretation" to Worship" with each contributor laying out the historical/confessional position of their given camp. Not much conversation is had which is what really disappointed me.
Kolb does a great job giving the reader insight into Luther's theology, with a bit of information on his followers, which proved to be helpful for me as a Reformed type. His use of Luther's catechism is especially helpful. However, while differences are mentioned, the authors do not go very far beyond presenting their position. What may have been helpful, though it would have doubtless made the book longer, would be a presentation of the respective positions followed by a reflection/response from the other side. Instead it seems the reader merely gets an introduction to each system, which could have been found elsehwere.
It is interesting to see the role that Luther plays for Lutherans in their theology vis-à-vis the Reformed system of doctrine. Kolb almost exclusively speaks of what Luther taught and compares it to some of what came after him. On the other hand, Trueman uses a number of resources from Calvin to the Westminster Standards to Bavinck without giving primacy to anything specific.
The interesting part about conversations between these two camps is that, in the end, in order to accomplish unity in doctrine, one side is going to have to humbly admit the fault of their confessions/history - something that neither is willing to do. This makes one wonder if visible, ecclesiastical unity is ever to be had. If I am to be honest, I don't think it will since the moment one drops their history/confession they cease to be Reformed or Lutheran and simply move to the other side. Where I do believe unity will be seen is in how the ecclesiastical bodies recognize and work with each eachother in the future while maintaining their doctrinal differences.
Overall, I would heartily recommend this books to someone from a broad evangelical background who is trying to understand the Lutheran and Reformed faiths. What is presented is clear, informative, and helpful for getting a grasp on both sides.