Final Fantasy XIII will not require you to adhere to the mandatory install feature, which is pretty good for those of you whom are losing space on your PlayStation 3.
Though the game is still a long ways off for those of us in North America, the game is reaching its release date over in Japan, coming this December. Though there is no mandatory install, the game will have a load time during the transitions from towns to field. But once you are in the open field, there are no more load screens, as it becomes an open world. Square Enix has been searching for ways to lessen load times, which has seemingly paid off. Many PlayStation 3 games require a mandatory install, which is taking up a lot of space on the hard drive. So it may be a relief to some that a game of this magnitude does not require one.
An install feature might have helped completely remove, or greatly reduce, the need for in-game load times, however. So maybe Square Enix will offer an optional install, for those of you interested. On a side note, Square Enix has revealed that Final Fantasy XIII will be sporting a trophy system as well.