The plot is like a B horror movie. That's one thing.
Two, the mechanics are insanely convoluted, to the point that even in the remake, with its reworked translation, I really have no clue how the element system works.
It's a weird hybrid of first- and third-person and the 3D dungeons look ugly as sin.
The random encounters are not only insanely frequent, but hard as smurf, so good luck going anywhere. Because they're everywhere. Even in the mall in between healing spots, shops, and the Velvet room.
Thankfully, the two Persona 2 games fix most of those issues, and while they're less accessible than 3 or 4, they're still really good games, which I honestly can't say about Persona 1. I'll take Dancing All Night over it any day of the week.