My impression of mega-churches has always been pretty negative. But now the church I attend has grown to the size that it is one, my views have changed with first-hand experience.
At my church, there's a sermon every service. Usually a straight-up, Bible-oriented, challenging sermon. But not "challenging" in the sense of churches I used to attend, where the measure of challenging was how guilty you felt when you left.
Shouldn't we have a sense of our guilt after a service? If done correctly we should also leave with the joy of our salvation from the knowledge of our guilt.