I've never beaten any of the games in the franchise, but I love that they exist, and what they do with the medium. No other RPG out there tries to explore the darkness of humanity the way this series does. I don't even need all the symbolism and metaphor. I enjoy that they are dark and mature as well. But they aren't doing it in a tryhard fashion the way something like Texas Chainsaw Massacre would. Their darkness and themes have purpose. It's not mature just to be mature, it's mature because it has to be in order to convey the things it wants. And unlike most JRPGs they tend to have more realistic characters, realistic drama, etc. The Persona games definitely make use of their tropes and anime archetypes. But they try to create them into real people, and not so much a paint-by-numbers character design. So it's more like "what if you met a real tsudare type person", rather than "this person needs to be tsudare so we'll do X, Y, and Z with them". So even outside of the dark and mature things I enjoy about them I trust them to do Japanese RPGs better than most Japanese companies

My one and only gripe with the series is how much it likes to use kids to convey its themes, it almost insinuates adults would be boring to play as reacting to the end of the world being overrun by demons. And adults have no self discovery and growth when facing such adversity. It's the one "Japanese" tropey thing they stick to even with a good portion of the series outside of Persona, adolescent coming of age