I think one of the most jarring things about DKR is that it's a pre-1989 and BTAS Batman. So Gotham doesn't look quite as gothic and dark(though there's some cases of art deco architecture visible), and Batman is far more wordy than people would be used to.
Neither of these things is that distant from Batman comics of the time(there are some 70's and 80's Batman comics with gothic ambiance, but it wasn't a constant. Batman still existed in a modern day setting), and Batman in general is far more talkative than he would become in later years.
A lot of people get told DKR is what changed Batmn, but it's really more of a major point of transition between the 70's and 90's.