I had enough of the emerging church when it was clear that those at the forefront were not only abandoning orthodox theology but sliding steadily into 19th Century Protestant liberalism. For example, last fall Diana Butler Bass (an early leader of the emerging church) all but admitted that she had moved beyond the somewhat orthodox scholar N.T. Wright to Marcus Borg, a man who denies the resurrection of Jesus. Bass defended Borg (against Tony Jones of all people) by stating that although Borg does not believe in the historical reliability of the resurrection accounts that he still is willing to recite the historic creeds of Christianity. Bass thought this was stunning but anybody who knows anything about 19th century liberal protestantism knows that even the most liberal of the liberal pluralists were willing to do that. What is even more disturbing is that Bass seems to be only a few steps ahead of Brian McLaren, Doug Pagitt and other leaders of Emergent in their suicidal slide into pluralistic nonsense which is really only a more "intellectual" version of the new age dribble doled about by the likes of Oprah!
Forget the aforementioned poor arguments, iconoclasm and easy embrace of political liberalism in which the emergents are being duped by the Democrats just as the emergents accuse evangelicals of being co opted by the Republicans (and I have Leonard Sweet to back me up on that!). The simple truth is that the slide into romantic, naive, pluralism proved to be a nightmare for the church once and will surely be so again.
All that being said, the reason Emergent has grown from a few seminary geeks in the late '90's like me to a whole lot of seminary geeks today is that emergents are very good at speaking the language of Generations X & Y. Rob Bell said it best when responding to a question as to why Mars Hill Bible Church exploded he said, in essence, that Mars Hill speaks this generation's "mother tongue."
According to just about every careful study, currently there is a generational gap unlike anything anyone has seen before. The gap is even greater than that which separated the 1950's from the 1960's. Evangelicals can learn a lot from Bell's style (as well as McLaren's, Pagitt's, etc.) just as the emergents could learn a lot from evangelicals theologically if they ever dropped the smug flippancy and actually carefully considered what was being said.