Something I've been thinking about recently, was the reception to Nero and how it might have improved if he was depicted differently.
Namely I was wondering if making him implied to be the son of Vergil was a mistake in hindsight because it felt like they were trying to phase Dante out with someone who was very little different from his DMC3 self. Perhaps it might have been better to have him be the reincarnation of Sparda instead of his descendant, in the vein of Soma Cruz from Castlevania. It would potentially justify the uniqueness of his Devil Bringer since we don't see other hybrids suffer the same issue and you could explain it as a human body being imbalanced by housing a demon's soul. I dunno, as cool as it was, the Devil Bringer always frustrated me as there's no in-game explanation of where it comes from and Nero never questions nor gets answers for his inhuman nature (in 4 at least). The reincarnation angle would also make Sanctus look less stupid for trying to go after Dante when he had Vergil's son under his command all along. Also by making Nero originally a standard human, it could have been interesting to make him start out more of an everyman who reacts more "normal" to the supernatural before gradually learning to go along with the flow, instead of having him be just as flippant as Dante typically is from the start.
This was very scattershot stream of consciousness, so don't take it too seriously.