You can split Persona 3 FES: The Journey into 5 categories: dungeon crawling and velvet room gameplay, time management gameplay, main story, and side story.

The dungeon crawling is surprisingly good. The game slowly introduces mechanics, and it keeps the gameplay fresh throughout by having new enemies to fight every ingame month or so. Combined with the velvet room, where you get optional side missions to kill x number of a certain kind of enemy by a certain date, get to a specific floor by a certain date, and where you can fuse together your pokemon-like personas into better/different ones, and it's some of the most compelling JRPG gameplay I've ever played. Granted it's also the most modern JRPG I've ever played, but still, it's great stuff. People complain about not being able to control your party members, but like, they're people. You learn how they work, and issue commands that you learn how they follow. If you can't get one to do what you need to be done for a certain boss, you switch them out for someone else who can. They're not avatars, they're people, and that's pretty cool. Yeah it can be frustrating, but that's the game idk. When a game puts in difficulty, that's part of the game and part of the challenge and part of what makes the game fun. What's not fun is the section of the game where many of the enemies have instant death, but you don't yet have the abilities to avoid the instant death. I must have lost like five hours of gameplay to bullshit like that. Not a fan. But most of the game is not like that.

The time management gameplay is intimidating at first, and kinda requires a little save scumming, which can be tedious, but once you get it, it's fun to work around things and decide when to hang out with who to advance everything.

The side stories in that time management though... it's not written well, and it's fucked up. You basically play a sociopath who hangs out with people in order to improve social links so that you can make better weapons personas. The optimal thing to do is to date 4 girls at once, never hang out with a girl again once she's your girlfriend, and agree with everything anyone ever tells you because you're more of a therapist than a friend and they'll like you more that way, thus raising those social links. You have the personality of a dull doorknob, and everyone loves you. And the game praises you so frickin much for... listening to other people talk and never disagreeing. What the fuck.

The main story is spread really thin throughout the game. You have a bunch at the starting, which raises a bunch of questions that you proceed to slowly forget about over the course of 130 hours of gameplay (most of them are never answered), and then a very slow dripfeed of story every ingame month, with I think two points near the end where the story actually goes somewhere. And said story is not actually good. It's dumb saving the world shit that's incredibly melodramatic and... very anime. Speaking of which, there are some problematic anime tropes in this game like objectifying clothing you can give to your female party members, horrible treatment of a trans character, general objectifying of women, the bathhouse peaking scene, more I can't remember. The game doesn't get so much flack for it I think because it's 130 hours long with probably about an hour total of objectionable content, but still, not cool.

So yeah, gameplay is cool, story is lame. I imagine this game is probably fully eclipsed by Persona 4 and 5 considering how much better the writing could be, and some annoying quality of life things in this one like not being able to read what abilities do other than when you have to ditch one because you don't have space for all of them