Radical Together by David Platt is probably one of the most brutal books I've ever read, but I absolutely loved it. It was better than Radical, in my opinion, because Platt clears up some of the things he said in Radical. For example, he talks about how we will never be radical enough or obedient enough or make enough disciples to be accepted and loved by God. Therefore, we must rest in Christ's obedience and sufficiency. Also, rather than making blanket statements about how all Christians should live, Platt simply talks about what The Church at Brook Hills does: their obedience, their failures, their plans. He emphasizes the need not only for local "missional living," but also for international missions and he explains how the 2 go hand-in-hand.
This is probably the most challenging book I've ever read. I definitely recommend it for every pastor, youth leader, Sunday school teacher, and church member.