I started replaying this game as I've only played it once before a long time ago. This game is freaking TOUGH. I'd say it's the toughest Final Fantasy game ever. The License Board is one of the greatest implements in the franchise, though. I love the Gambit system, too.
The voice acting is FANTASTIC. The best I've heard on a JRPG.
12 was easy as fuck dude. Unless you mean optional monsters gave you trouble.
One or two of the optional monsters were "Hard", as in a marathon, but none were as difficult as most think. Yiazmat was just annoying because of the time commitment, but not hard.
Omega Mark 12 could have been hard, but they nerfed his HP for North Americans.
Zodiark was supposedly hard for some people. But I did not find him that tough. Once you figured out when he switched up defenses, you just adjusted accordingly. Easy
The story itself was easy as shit
I played maybe 3/4 of the game really trying to get through it despite not enjoying it at all. I didn't like the story, characters or wannabe online rpg gameplay.
After 10 it was a huge let down and signalled the death of my interest in new FF games.
I hope someday they recover from it and go back to pre-12 style.
The story was shit. The gameplay was awesome. Mostly open world and with enough versatility. It was back to the style of 6 in terms of no real main character and ability to rove and explore.
10 was a huge pile of shit in terms of gameplay, linear as fuck, and with a whiny emo main character who made Squall look normal. At least Squall quietly brooded instead of throwing kiddy tantrums and saying daddy didn't hug me enough and tried to toughen me up because I was a huge wimp.
Tidus should have been a secondary character with Auron running as the main. Impossible to empathize with Tidus as a person.
12 was a tremendous improvement over 10 in gameplay and world, but 13 was back to 10 style linearity with shitbag characters.
Most people who hate 12 also were not fans of early JRPG's. They want to run through the story without doing the extras + grinding and judge the game based on that.
Most of the people who love FF1, 2 and 3 for the NES and Japan NES(I mean the original 2, and 3, not 4 and 6) enjoy 12.