One of the biggest mistakes scholars make is by overemphasising the postmodern aspect of the movement. But let me make clear before going any further: understanding postmodernism is critical to understand the Emerging Church. Emergents admit this repeatedly throughout their writings, their blogs, their articles, their "conversation." However, the problem becomes whenever we take it too far. Emergents are not, for the most part, associated with the far far wing of postmodernity. They believe in truth, but do not believe that one person, or one source (Scripture for example) contains all truth. Their version of "relativism" insists on community, an ongoing conversation, and inter religious dialogue.
A recent book that I have read is "Truth and a New Kind of Christian: Emerging Effects of Postmodernism in the Church" by Dr. R. Scott Smith makes this mistake. Dr. Smith offers a great review and critique of postmodernity and applies it to the Emerging Church. Most of what he says is correct. Therefore, this book provides helpful insight into what postmodernity is and how it affects the Emerging Church. However, I feel that Dr. Smith knows more about postmodernism than the Emerging Church.
Dr. Smith offers, for the most part, a great critique of Brian McLaren and others, but just takes postmodern philosophy too far. It seems that once persons hear that Emergents are postmodern, they critique Emergents by critiquing postmodernism. This is all well and good, but limited. Postmodernism is only part of what the Emerging Church is and to only focus on this aspect alone is to limit oneself to a more complete critique of the movement. Perhaps this is why Dr. Smith limits himself, for the most part, to only a few of the major Emergent leaders.
Overall, for those who have studied this movement in great detail, I would recommend this book. However, it is rather deep, philosophical, and difficult at times. Dr. Smith offers a great review on postmodernism and applies it to the Emerging Church. But to anyone who has read and followed Emergents themselves, I believe you will find that perhaps he takes things farther than Emergents would allow.