I don't think it is overrated, simply because it is a completely type of different movie with completely different approaches to Joker. I liked Joker for what it was (and it was honestly a breeze of fresh-air into DC and Marvel super-hero movies) but i don't think anyone would ever claim that Joker is overrated when comparing to Batman: Dark Knight, simply because Batman: Dark Knight is a much bigger-scope movie, It was a very good movie (considering it was a Super-Hero movie), i would even say that entire Batman Trilogy is a beacon of light in Super-Hero movies because it mixes real movie-making (in traditional sense) with the inherently non-sense comic-book stuff in the perfect amount... and Heath Ledger managed to become the star in that entire trilogy imo. That being said, i really liked how Joaquin Phoenix played Joker given what kind of movie Joker was, and i would actually like to see him playing Joker in future DC mainstream movies because i do think Joaquin Phoenix could pull-off a very good Joker in a more action-driven movie. Imo Heath Ledger is still the best Joker (and one of the best performances ever in mainstream-Hollywood-movies), but Joaquin Phoenix is, by very far, my 2nd favorite. I honestly just don't see how Joker (2019) is overrated.