12 did not have a smooth battle system. It just had a smooth transitioning between battle and travelling. 13 did keep the original FF style with at least coming into a battle scene, hearing that beginning of the battle theme that were not existent in 12 again getting ready for a battle you know is going to be epic.
I have to say that 13's battle system was epic, but it had no dungeon feel in it. It had no struggle for survival in it. You never thought "Will my mana last until the end of the dungeon?", "I've got only 10 potions, I should get some before going in here" nor "I've got just 3 phoenix downs, I should get more just in case".
It had no mana, instead you paid with the time in the ATB bars, it auto replenished health, making potions obsolete, it reset status ailments and K.O's after every battle. There is no dungeon crawler feel in it. D: