Problem for me is I saw the ending coming a mile away. Killing the Green Lanterns was an initial shock but then the writers overplayed it. As soon as they killed off Superman and Batman, I immediately lost interest because it obvious that the whole thing was either going to be a dream or hallucination and everything that would happen in the next 20 minutes wouldn't matter.
This wasn't even a good example of this type of premise, Wiseman's other show "Gargoyles" at least did a much better job. If they're going to go for a dream episode, at least dig into how things could really be different is certain details were changed. Just having a faceless threat kill off everyone one after another one, is boring.