Unlike in previous Final Fantasy games, in Final Fantasy XII, the monsters / enemies will have a high level of artificial intelligence, allowing them free movement and thought. Thus, they will be able to manipulate the player in a number of interesting and intricate ways. It seems the player will now have to make full use of the map to discover where enemies are, though be warned – they may plan surprise attacks on you when you least expect them!
These enemies may, furthermore, join in attacks to help other enemies, making the overall battle experience more unique and less linear than previous Final Fantasy games. Monsters will also take much more notice of their surroundings in Final Fantasy XII; how much they will be able to attempt to such conditions is yet to be seen.
Even normal monsters in Final Fantasy XII will be able to flee from battles, and presumably heal themselves in a similar way to playable characters.
Lastly, it should be noted that, similar to Final Fantasy XI, enemies will be able to sense your presence in three different ways; sight, spell and sound. This should make playing the game a more heightened experience than previous games.