What set this particular documentary apart from others of its ilk is that all of the apocalyptic prophesies were presented by actual scientists, who described the effects of each scenario were it true before issuing a very short disclaimer at the end of each segment that the alternative theory is untrue. Strictly speaking, this documentary ought to have been perfect for me since it had a skeptical perspective on a very silly idea. (Quick: How many previous doomsday predictions have come true? Answer: We're still here, aren't we?) But it wasn't.
The problem is that by having actual astrophysicists, geologists, and other scientists explaining these false theories and describing their potential effects in great detail, the program ended up giving greater weight to these flights of fancy than they otherwise deserved. On Ancient Aliens, it's easy to separate fact from fiction (if one is so inclined) because the conspiracy theories are presented by very obvious conspiracy theorists whose wackiness and flying leaps of (il)logic make their silliness manifest.
By contrast, if the accidental viewer did not watch to the end of a segment in 2012 Apocalypse, that viewer would come away with the impression that serious scientists take the the theories very seriously--an impression reinforced when noticing that the scientific rebuttal was many times shorter than the drawn-out orgy of computer-generated illustrations of the devastation awaiting us in just twelve months' time.
I can hardly wait for Apocalypse 2012 Revelations tonight.