We had a number of mega churches in TX. I always felt there was something "cultish" about them.
There is no doubt that there are churches who worship their style of worshipping.
That being said, I can't say that "seeker" churches are a bad thing. Here on Nashville's west side, we have a sort of hierachy of praise churches. One is a true seeker church and has a huge weekly attendance. A little down the street is one that introduces a little more Jesus but keeps the flash. Then you have the "graduate" churches - mine is one - that are fully biblical, yet still have the praise band, the Powerpoint slides, and the like.
Mine is a Methodist (yes, Methodist) congregation of about 1500 . We have 3 services on a Sunday, and our praise and worship service is a model for other churches - many have asked us to teach them how we do it. We are extremely lucky that we have two pastors that are quite conservative for Methodists (one is downright Pentecostal) .
We are gowing, yet we pray that we don't grow TOO big - one advantage we have over the megachurches is that at our church you can know EVERY SINGLE member by name, and feel part of the family.
Anyway, back on point - I think if a town has a multi-church path of "graduation" to solid, biblical Christianity, seeker churches have an appropriate place. Get 'em in the door, and Jesus will do the rest himself.