It's been a long time since I played the original on the PS2 but I still notice a clear difference. Sure, it's a remastered game not a complete remake but they still updated the character models to make everything feel new and sparkly. It looks great! The music is updated too and feels more natural, it's the same tunes, just reorchestrated. Other news is the extra content that wasn't in the original English releases. There should be some new bosses and stuff. Kinda like the Kingdom Hearts remixes... But overall the game is pretty much the same as the original.
If you're an FF fan but never picked these up back in the day now's the chance to do so and play them the best way possible. If you've already played them but really liked them well why not play them again. The game has a very fair price, but if you wanna save even more there's always the standard edition without the art book. Same game content. Either one will probably satisfy you, depends on if you really want that art book or not. About that, there aren't many character art pictures in it but there's some really cool concept and environment paintings as well as some monsters and logos. It's a hardcover book but thin like a smaller children's picture book. lol
My only complaint is that they should have included the Japanese voice track since the mouths don't match the English dialogues. Looks occasionally derpy but I guess if you aren't picky it wont bother you much. The English dub is still high quality and voices are very fitting. My fav actor is probably Wakka's actor, it's like he was born to do his voice!
Two great Square Enix RPGs in HD, can't get much better. Right?