1.) Strategy and preparation are absolutely critical. Unlike in other rpgs where you can just farm your way to overwhelming strength and brute force, 13 forces you to think before and during battles. You can't even beat some regular random monsters without strategy and the right party.

2.) Degree of customization is leagues ahead of the competition. Gone are the days that you must keep the main character of the game in battle. You can put anyone in the battle team and give each of them any role you want. Gone also are the days that experience is automatically given and characters have a linear progression path. You can assign experience points as you see fit, depending on the role you want a certain character to play. Gone also are the days that weapon and armor progression follow the "oh, that weapon/armor is better" path. Weapons/accessories can be upgraded as you see fit, each weapon serving a different role for a different kind of battle.

3.) Each character has unique strengths and abilities that will make you constantly change your battle team. There are no "must have" characters and no "useless" ones, unlike in other rpgs where you have a specific team that you build up. All characters advance together, even though they're not in the battle team, keeping them all balanced.

4.) The mana bar is gone, making battles far more fast paced than ever. The mana bar has always been the most limiting thing in every rpg, and 13 eliminates that. You can cast any spell you want whenever you want, giving you far more freedom to move and do battle as you see fit.

5.) You directly control only one person, giving you more hands-on experience with the battle, while assigning the cpu to control the other two. This adds to the fast paced nature of the battle, since you don't have to tell each member what to do exactly every time their action bar fills up.

In short, it's fast paced, exciting, intelligent, and strategic at the same time.

no, there is a major flaw to it..

buffing/debuffing and reviving

the party members are not seldomly doing the wrong buffs (f*cking do haste and protes first damned Hope) and prioritise healing ~80% full members to raising a dead one

and they don't debuff "slow" quickly enough either .. really, that spell can screw one up in this game more than almost every other (of course "pain", "stop" and "fog" are pretty wicked as well)

Yeah, FFXIII's combat system is amazing.

it does have its flaws, such as reviving which is a major pain cause i end up just using a phoenix down as its faster than waiting for them to cast Raise and buffing is in an odd order, protect and shell should be first and then everything else but its like Faith/Bravery first then everything else same for buffing, Dispel first and then Slow and then everything else but its Imperil first, maybe thats how its normally done in Japan and they just coded that but it is annoying.
However i do agree with you that it is one of the best battle systems yet, FFX i liked because you could take your time but FFXIII i like because you have to think quickly :) and the paradigms are awesome.

No. it's the second best, the best is X-2's, it's fast paced, challenging, strategic and looks cool.

I really enjoy it :) One of the best... Then again I love the junction system to due to the complexity of it. anyways it's fast and complex enough to enjoy... My only gripe is once you die you die!!! Why?

yeah that is a pain, but you do have the choice to retry if you die which i think makes up for it

I actually liked Star Ocean 4's better. But this is the best one on a Final Fantasy. For some reason it feels weird now, not being able to run around in battles when the action doesn't wait for you.

Yeah, that annoys me too, but I still think it is a great system

its a great system but i like the tales series battle system the best.