Pretty much everything aside from a few tracks from the soundtrack. I've stated my opinions in detail many times over the years, but here's the gist of it:

Gameplay: the Crystarium is bulltrout right off the bat. They basically decided to take the worst aspect of the original sphere grid, it's linearity, and crank it up to 11. There's no actual choice for the player there until extremely late in the game.

Which is actually one of the bigger problems with the game as a whole. Everything is held back far longer than it should be. You don't even start getting exposed to leveling up and the different roles until 5+ hours in. Which might not be so bad if the characters had a decent variety of abilities before that but, of course, they don't.

And speaking of those roles, the idea that paradigms offered any interesting strategies is a joke because you can get through the entire game with two of them, maybe three if you want to throw in some status effects, but it isn't necessary. Playing a game where you mash auto-battle to attack, then switch to a healing paradigm when you're low on health and mash auto-battle some more gets old fast. Playing it for more than 30 hours moves past the realm of got old into kill me now please.

Story: pretty awful overall. First up we have reading the in game dictionary to learn information essential to understanding the story. That's just plain bad and there's no justification for it. Then you've got the fact that the plot doesn't really go anywhere for the first several chapters. There's no real goal or plan other than run and/or fight back. Very little actually happens, and it's only made worse by the characters motivations and development over that time.

Hope wants to kill Snow for getting his mother killed, even though that's not actually what happened and Hope was there to see the whole damn thing. Lightning encourages him to get revenge, then as soon as he's committed to the idea of killing him she's suddenly shifted into "holy trout you want to kill him?" mode and tries to talk him out of it. This shift in her attitude comes out of nowhere of course because the developers just decided she suddenly needed to feel that way. And for 90% of the game Vanille knows pretty much everything that's going on, but hey, why bother telling anyone. This is probably the biggest group of morons assembled in an RPG in a long time. Only Sazh actually makes sense throughout the game.

Graphics: it doesn't do anything interesting on a technical level, but that's not a huge problem. Not every game actually needs to push the limits of modern tech. But what's unforgivable is how awful the enemy and level designs are. The enemies are almost entirely a visual mess. Making out what they're supposed to be is difficult most of the time, and I have to question the skills of the artists that actually made them. They basically suffer from the same problems as Nomura's Batman. There's lines and details added that don't actually add anything to them other than clutter making the designs visually confusing and just plain ugly.

Cocoon isn't a lot better since most of the environments make little actual sense (I still don't know how all of those different parts exist inside a sphere in the sky) and it's all extremely linear and most of the interesting stuff you see are just skyboxes you'll never interact with.

I could probably keep going, but class starts in five minutes.