Spoiler goodness for 1984, FFX, and FF12.
The battle system pwns. In all the ways that "pwn" means. The battle system defeats and embarrasses (in such a way that the defeat and embarrassment feed off one another reaching an unusually high level of reaction) all other battle systems in comparable games (that I've played (which, I admit, is limited to FF12, FFX, and FFT&A)). The battle system in Twelve kills the battle systems used in comparable games, as it kicks total ass; being better than them, it out-competes them and will supercede them. The battle system wins--is indeed made of win.
The player can walk the fuck around enemies that they don't want to fight. Not just a lack of random encounters, but having encounters dependent upon the will and skill of the player, just as many things in real life are available--from sex to success in investment, if you want to get laid, avoid The Clap, get rich, or stay poor, depending on what you want and how skillful you are, your chances to get what you may get change in a reasonable fashion. No tricks. No cheats. No dances. Just the analog control stick and a lack of having a seizure and you're safe.
The free-swinging camera is the shit. When I first got Twelve, I played with that thing and had so much fun. Of course I set the mode to Wait, so I'd just have to press X to basically pause, and I'd do just that and swing the view over to a dramatic angle with the desert-dwelling wolf I was fighting on the left side of the screen looking into the background, with Vaan on the right, facing into the foreground, looking at the wolf, sword drawn, with a big, blue hyperbola connecting him to his target. Sand whips up amidst the battle, and the beautiful desert formations stand behind, uninterested.
After I got Fran, just as she was about to release an arrow, I'd swing behind her head for a good look--all dramatic-like. It was the shit.
Hey, look, x equals -b/(2a). Now for the downside.
It was a story of events; not characters. Characters are compelling, as are emotions, tugging on the right hemisphere of the brain and my social and emotional components and keeping me interesting and coming back.
The dialogue was awkward even for the "style they were going for". It was too high-fantasy-style. I don't expect to get the kind of dialogue that I'd put into a fantasy novel (which would be low or dark fantasy the whole way) since, though sex sells, selling too much sex is to sell H.I.V. and that's bad for business so they just stick to short skirts for the chick characters. Bad metaphor. (Bad metaphor! Don't pee in the house!)
Basch was a goddamn map. No character, no personality, just a habit of telling everybody where they're going and how. Annoying.
Vayne totally looked like Seymour from FFX, so making him do a two-faced turnabout was a little expected. What was unexpected and bad was that there's no real reason given for this. He just likes power that much? He shows awfully no emotion for it. Seymour at least tried to seduce the party into helping him a few times with a dream-like feel to his voice. In just such a state he said "Allow Kimahri to die and release him from his suffering. Spira, is consumed by the spiral of death. To destroy - to save Spira, I will become Sin with your help Lady Yuna." Seymour was a fucking badass--albeit batshit crazy. He is O'Brien minus Room 101; the party is Winston minus being locked up in Miniluv and tortured.
Vayne's bullshit switch to total ass is an instance of FF12's being a story of events and not characters or motivations. The why is the most compelling thing, with which Ten is rife. Another is Balthier's actions taken due to his notion that he's the "leading man". He occasionally provides a big giant pixel that says "I'M THE LEADING MAN REMEMBER GUYS" but acts like just another supporting character all the rest of the time.
Last is the repetition of music. This wasn't the case in Ten at all. In Twelve, though, the same music plays in the Tchita Uplands as in the Giza Plains, and several other pairs exist. In all these cases, trying to have one piece that suits both locations has created one that suits neither. It characterizes neither place and is obnoxious--at least for the Giza-Tchita pairing. Again, a lack of characterization plagues this game.
Overall, the camera, battle system, ability to swing the camera around while making decisions in battle, and the ability to walk the fuck around enemies that you don't want to fight make this game great. It's great instead of awesome 'cause the story lacks any right-hemisphere-y goodness at all.
When I'm less ranted out from, y'know, not ranting/analysing for a while, I might write up "Why Final Fantasy X is awesome", which will take some time.