The AI are too bot-like. In previous halo games the AI constantly moved around the battlefield in an unpredictable manner in accordance to the location of the player. This made flanking and other tactical maneuvers more challenging as the enemies would often be ready for you when you emerged to attack. This was made even better in reach with the AI outright pursuing you at some points, forcing you into retreat.
In halo 4 the AI are very stagnant and predictable, grunts and crawlers simply advance until they die while elites, knights and all the other enemies simply stand in the exact same spot waiting for you to reappear, moving only when they are unaware of your presence. This make the gameplay too easy as you hardly need promethean vision to tell where enemies are and can kill them easily once you work out their attack patterns.
The other problem with the AI, which I really hate, is their ability to watch the player at all times. This kind of behaviour is typical of older games where the AI always knows where the player is and is simply programmed to not attack them until they get a direct line of sight. This can easily be spotted by taking active camo and walking round an enemy in a circle or going round a large rock and looking in promethean vision, they literally watch you the whole time.
I feel this was implemented to prevent easy assassinations since the enemies just stand around most of the the time but it really kills the sandbox capacity of the game. Want to flank the enemies to the right? NOPE, they’re already shooting you the moment you emerge. In older halo games, even CE, the AI went on a last known position basis, supressing the area with plasma fire and even tossing grenades on occassion. This made the game more challenging when you were fighting in a choke point and allowed greater creativity when assaulting rooms with multiple entrances.
So here is my request to 343, please remake the AI for the next halo game. The combat in halo 4 is simply not challenging/creative enough to be enganing as it was in previous games. Not to bash on the overall campaign mind you, for the most part it was very good.