I'm about 8 hours into this game, i'll give a quick review on this.
Pros -
1. Awesome battle formation system, you can customize your strategies which is useful. You can also level up your battle formations.
2. The battles flow very seamlessly and the action is plentiful. People are shooting off spells, guns, swinging swords, flipping, dodging, you name it.
3. The summons are as fun as ever, and earning them is pretty cool too.
4. The fact that the mouths were redone for the english language is pretty cool.
5. The weapon creation system is neat. You actually level your weapons.
6. The enemies fight each other too, which leads to 3 way battles when you enter.
7. Lightning.
8. The stagger system is cool too. Gotta weaken your enemy before you utterly destroy them.
Cons -
1. Hope.
2. You don't level up in this game, you just level your abilities and weapons.
3. The ability level system is a dumbed down version of the FFX level system.
4. The graphics look like someone took a crap on my television screen and i'm playing in it. (I bought the 360 ver. the ps3 ver. looks great however)
5. No open world exploration, feels kind of like i'm playing phantasy star online.
6. The music is entirely forgettable.
7. The story so far is very predictable.
8. There's only 2 stats in the game, Str and Mag.
Overall, it's really not that bad. Maybe not worth buying but i would say it's worth renting. I still haven't played a worse FF game than crisis core, that game made me want to puke blood. X was alright, X-2 was like playing with barbies, and 12 had very backstreet boy looking male characters and a mmo playstyle which doesn't really work in a single player game.
Note - my opinion may change as i progress through the game for better or worse.