Does Jhin go even or excels against any mid?

He can do mediocre there. There are probably a few favorable matchups, like against support type mids. He can farm effectively and if he lands his skillshot, he's decent at backing up ganks. But he's just way more mediocre than other mids you could have.

Right now, he is mediocre in both positions. Requires an insane amount of micromanaging ALL game to be good at and really excel. His late game scaling is insane, though...Play him safely all game and focus on farming and come lvl 13+ you are a monster (considering you know how to play him...which most people dont).