I finished it earlier - aesthetically at least, I think it's super good! Vanilla Dark Souls 3 kind of left me wishing its "end of the end of the world" premise showed itself a little bit more in its environments, and The Ringed City totally delivers on that. The music is fucking great, too, especially those violins in Darkeater Midir's theme.
As someone who's into these games for reasons other than their hardcore, crushing difficulty or whatever, I thought some parts of it were definitely frustrating - the angels in the beginning areas are some sadistic nonsense, and I don't think I ever really figured out the way the designers intended you to deal with the big dudes who summon a bunch of fiery silver knights at you. They at least have some pretty cool mechanics around them that I can appreciate though, and the last boss in particular was fun as hell.
I don't really know how I feel about this expansion being ostensibly the last bit of Dark Souls there will ever be, story-wise. Environmentally I think it's a perfect ending for the series, but I think there needs to be one other cutscene or something with the painter to tie things together a little bit more cohesively (even for Souls storytelling standards). Also, maybe I'm just missing something, but I feel like there are so many different statues and snake-related things in this DLC (and the rest of DS3, too) that Frampt or Kaathe had to make an appearance, and I was kind of bummed out when they didn't. Those guys are just too weird and big to not show up again in the series.