Most of the problems with the plot are tangental to true spoilers, so luckily, it's not hard to talk around it. That said, P4 does have a fantastic twist, as it's a murder mystery game for most of it and finding the identity of the killer is a huge part of it. So, if you've avoided spoilers so far, I'd try your best to keep it that way.

All of the Persona games are little poor in the way many Japanese games are with gender, sexuality, et al. But P4 is especially bad about it with one of its main characters very gender bendy and basically their lesson in the game is that, they'll never pass as anything but their birth assigned gender for their character arc. There's a decent amount of fat jokes that are in poor taste. There's homophobic humor wrung out of another main character's non-gender conforming interests and passions. There's another main character that has a non-traditional career, but they are pushed toward something that's more gender appropriate. Because a lot of the game revolves around overcoming your "shadow-self" and pushing out bad thoughts, it gets kind of dicey for character arcs. Basically the message being, there are certain core things about yourself you can never change and you need to accept that; bur rather than liberating, it's stifling.

All that said, if you can get past that stuff, it's still a reasonably good story with what some people consider the best cast of characters in the series. I certainly wouldn't say avoid it, but know you're going into a plot with social ideas that are flat out regressive, especially by today's standards.