The screenplay, music, and acting, all combined with a story that puts you in an environment that is deeply unsettling and is sure to leave a mark. Undoubtedly one of the best iteration of the clown prince. Whereas Heath Ledger's Joker was more psychotic than a comedian, Joaquin's Joker successfully achieves the attribute of the psychotic clown that stirs up Gotham into chaos. And Gotham couldn't have been depicted more perfectly I believe, an actually city of madness.
Get ready for a goosbumps trip.