I've definitely seen people complain about Persona's length online, and I even have 2 good friends who love JRPGs but can't get into Persona (no matter how many times I've tried).
I even bought P5R for one of these friends, and he's started it 3 times, but never even makes it more than 5 or 6 hours in before giving up due to the extensive slow setup.
I don't think length is the main issue though, I think it's all the story, cutscenes, taking control away from the player, dialogue, etc. At the beginning. I know it's meant to establish the story, but most other JRPGs & narrative-focused games find a way to get through this much faster (and balance it with more gameplay).
I know what to expect & how good things get, but others do not. A lot of people said the Metaphor demo turned them off to the game, which I can only assume is because they're not used to that first 3 or 4 hour setup
