The recurring themes of so many of the 10 star reviews here should tell you a lot about this movie and its audience. If you can't get through a movie review without tossing in one or more claims that "THIS movie is so much better and smarter than YOUR superhero movie" (or even basing your entire review around this premise), then I hate to break it to you, but kid, you're nowhere near as intelligent and grown up as you think you are. This "my comic publisher is better than yours" BS should have been left behind on your grade school playground, it has absolutely no relevance to the quality of this movie, and your opinion of this movie should be considered highly suspect if you're in this group.
I gotta say, if this movie was also your idea of the most perfect film ever made, you really need to get out more. Look, I get it. If you live in a safe little box where all you watch are superhero movies and mainstream blockbusters then I understand how exposure to themes like this for the first time would seem new and exciting to you, and I think we can all agree that this is probably the best DC Comics related movie in the last decade or so (though that's not a high bar to meet) and of course Joaquin Phoenix is a very talented actor, but stop and take a step back and look at this thing.
Joker does indeed present a theme that is of importance to our society, that of the neglect and demonizing of the mentally ill to a degree that sometimes creates monsters which everyone around them should have seen coming a mile away if they hadn't been too busy looking away to avoid feeling uncomfortable. Unfortunately, reminding us all of the fact that this situation still exists is all this movie really has to say. It dances around important subjects like "HEY KIDS, CLASS INEQUALITY!", but then never offers any actual insight into them, usually because it's too busy making forced Batman references or dropping cringey little edgy moments like the "Don't smile" sign scene which seem to have been designed solely to have something for Hot Topic to print a new t-shirt of. Between that and every single plot twist being telegraphed so very far in advance because a lot of us have seen all these exact same twists so very many times before, I just wasn't impressed.
Perhaps if this had been an actual stand-alone movie of its own instead of being shackled by its completely unnecessary ties to the Batman universe it could have done something more interesting with its themes. Don't get me wrong, I don't have any problem with superhero movies, but it just feels so gratuitous here, as if someone came up with this idea, pitched it to an executive, and was told "sounds great, but can you make it a Batman movie somehow?", and I'm sorry, but I'm just not into a movie trying to tell me a half-hearted, yet dead-serious speech about mental illness in modern society while simultaneously constantly reminding me that it's technically a superhero movie because $$$