These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: The Big O
Cult Classic: While not nearly as popular as manga that would come out in the following decade, it has a cult following. It being the last fully hand drawn anime series before its second season as well as its westernized style gives it a unique identity in the anime world.
Fan-Preferred Couple: Roger/Dorothy. In the English dub, this is made even more textual by Roger in season 2 by saying to a then deactivated Dorothy that if they had met in another time and another place and if Dorothy were human, then it would have been very likely that they would have fallen in love.
Dorothy's dub voice actress outright states Dorothy is in love with Roger.
Genius Bonus: The trippy opening sequence features newspaper clippings in the background, announcing veridical events such as the death of the 1950s jazz musician, Lester Young.
Nightmare Retardant: Schwarzwald is significantly less scary/intimidating when he looks uncannily like Getter 2 with all those bandages.
Suspiciously Similar Song: The opening theme sounds suspiciously similar to Queen's Flash Gordon theme. To the point that when Bandai remastered the series on DVD, they had to replace it with a new song. Meanwile, the second season's opening, "Respect," never even made it to the first DVD release - it was almost a note-for-note copy of Gerry Anderson's "UFO." Both openings ended up airing on Adult Swim.
Too Cool to Live: Schwarzwald, the only Megadeus pilot that ever gave Roger any real trouble. And the only proper Megadeus pilot other than Roger. Alan was deemed unworthy (the message was "ye guilty" instead of the usual "ye not guilty") and eaten by the revived Big Duo, and Alex's Big Fau shut down on its own accord ("ye not" instead of "ye not guilty", thus rejecting him as a Dominus) before 'merging' physically with him.