Was it a random phenomenon, or was it the biblical rapture? And even if one believes that God would whisk the faithful away, en masse, to heaven, how could it have been the rapture if the bad were taken along with the good?
The show focuses on how people deal with the event 3 years later more so than the event itself.
Summary of some of the early critic thoughts can be found here, which have been very positive over all.
The premiere is tonight 6/29/14 on HBO