There are interactions that have never been interacted before in KOF2002. I also really love the stages of Vanilla 2002. I think arguably the weakest aspect of the game is the music, but it is serviceable. I think overall, it's a good KOF.
Vanilla KOF2002 is pretty fire sometimes. Idk if I would classify it as "kusoge" as much as I hate that term, but I think it has it's own fair share of jank that makes it worth playing alongside the UM version. It answer many such questions such as, what if Billy was top 5?