I played the Call of Duty games and one of the most notable issues I encountered in the single player campaign was how the AI interacted with each other. Although they do somewhat of a decent job when shooting in distances between, when they get to close quarters where it gets very confusing and odd when witnessing one trying to attack.
 
I encountered a core partner trying to attack someone while another enemy seemingly charging at him. As they were about to get close, they passed each other like nothing happened and the enemy seemed to pass the other people behind him and got to me leading to my death. I find this very weird especially in the harder difficulty levels where your friendlies provide little to no help.
 
Another incident is sort of similar where an enemy and a multitude of allies pass each other in plain sight where anyone can see it and 5 seconds later they attack each other.
 
Although such things as smoke concealment can make sense but seeing it out in the open just doesn't.
 
If it does appear in Modern Warfare 2, I will try not to mind it (just endure) but Infinity Ward, Treyarch, or whoever would develop a Call of Duty using whatever IW engine (when it seems pretty much the id Tech 3 engine just beefed up constantly) must look at when working on a future iteration.

Yeah, I sure do hope this issue is resolved with MW2.  Every Call of Duty game has had wonky AI.  I'm also hoping they tweak the harder difficulty levels so the AI, instead of chucking a bazillion grenades, are actually both more numerous and smarter than normal.

There was some video preview where they were specifically saying they were going to make the AI feel way more intelligent in MW2.  They showcased some of the reactions the AI had.  I don't know if it'll be intelligent AI in a game sense, but it's supposed to feel more realistic in terms of humans.

I think it will have the same Dumb AI as it always has but that's just me. They do really need to fix it  though so on harder difficulties, The AI actually helps you a little bit. 

Enemies in call of duty games just hide behind cover, shoot and move backwards to another piece of cover if you move up and fire again. They dont do anything like flanking unless its a set piece in the game. The AI can break in close quarters because there is so much movement and the AI will always prioritise you first

Also that leaked bit of 9 minute gameplay looked like traditional call of duty.
Spawning out of nowhere (normally above) and just crouching there occasionaly standing up to shoot

my problem with mw was that the enemies would constantly respawn so killing dudes wasnt rewarded.

Im currently going back through MW on Veteran and some areas are just unrealistic to get through because the enemies throw so many grenades you get stuck in a corner. Its also ridiculous how an infinite number of guys will come at you until you hit a checkpoint, thats a little unfair.

You all are walking on thin ice. I posted a negative about the COD series AI problems and the neglect of addressing it thru each title and i got HAMMERED. Look, IW and Treyarch have created some great titles, but enemies that respawn over and over, they never have to reload, they dont change tactics is really dated programming IMO. I wish somone would ask them those type of questions instead of the same old, "whats multiplayer gonna be like?!"  

" I played the Call of Duty games and one of the most notable issues I encountered in the single player campaign was how the AI interacted with each other. Although they do somewhat of a decent job when shooting in distances between, when they get to close quarters where it gets very confusing and odd when witnessing one trying to attack.  I encountered a core partner trying to attack someone while another enemy seemingly charging at him. As they were about to get close, they passed each other like nothing happened and the enemy seemed to pass the other people behind him and got to me leading to my death. I find this very weird especially in the harder difficulty levels where your friendlies provide little to no help.  Another incident is sort of similar where an enemy and a multitude of allies pass each other in plain sight where anyone can see it and 5 seconds later they attack each other.  Although such things as smoke concealment can make sense but seeing it out in the open just doesn't. If it does appear in Modern Warfare 2, I will try not to mind it (just endure) but Infinity Ward, Treyarch, or whoever would develop a Call of Duty using whatever IW engine (when it seems pretty much the id Tech 3 engine just beefed up constantly) must look at when working on a future iteration. "

Less than challenging AI is one of the reasons why multiplayer is popular.  It's much more satisfying owning skilled human beings than predictable AI that can't shoot straight and has underpowered weapons.  Although, it would be great if AI was good enough to provide a sufficient training ground in preparation against human players.  BTW, I only played COD demos and they all felt like shooters on rails. "

I always hated your team-mates AI in CoD. I hope that's been resolved for Modern Warfare 2.

AI will be more realistic but I'm not too sure about intelligence. I heard that they will move for cover, try flanking you, etc. The AI during Veteran mode are just pure cheap ass AI. By the way I think the only time that your teammates do anything useful is in Mile High Club, more noticeably on difficulties less than Veteran.
 
@me3639: Its confirmed that in SP and Special Forces mode that there are a fixed limited number of enemies than a infinite respawn.

" AI will be more realistic but I'm not too sure about intelligence. I heard that they will move for cover, try flanking you, etc. The AI during Veteran mode are just pure cheap ass AI. By the way I think the only time that your teammates do anything useful is in Mile High Club, more noticeably on difficulties less than Veteran.
 
@me3639: Its confirmed that in SP and Special Forces mode that there are a fixed limited number of enemies than a infinite respawn. "

The AI always sucks in every video game, no matter how many times a dev says this is the most advanced AI we've used yet. Bullshit they are always retarded and will screw you up. Its time we get used to it.

probably....

Short answer yes.
 
Long Answer:As I have played Infinity ward games i have come to the conclusion that they can't make AI worth a damn, or level design for that matter.
COD2 by infinity ward has all the same problems that COD4 has enemy AI by passing all friendly AI and finding you and only you, and its not a matter of distance pop your head up? and you will have 5 guys shoot at you and only you, 6 grenades on your position, fuck the other AI thats killing them their goal in life is you, Getting shot through cover *level design* getting shot through the actual geometry.
 
COD3 has the same problems but its by treyarch and the problems are much much worse which leads me to believe the all ready rotten core of AI and level design by infinity ward is 
present so treyarch ends up messing it up even more. 
 
Oh and don't even get me started on invincible enemy glitches in both games, I never had so many problems where the game forgot to remove an enemies plus 80 armor because i had moved up, and im trying to shoot him with no result but he has no problem killing my ass.
 
If Infinity ward gets their shit together in AI, Level design and not using unlimited sometimes invincible enemies then it will be a great game, But till then it seems that the only way they can make a game actually hard is by making them cheap, and allowing them to cheat.
 
I'm currently on cod3 360 as canadians trying to get the last 88 gun next to a house, with about 20 enemies that continue to flood out of the house, finally till i can get near the house and unless i get inside the house the central enemy behind a box is invincible i then have to deal with the guys in the back of the house, till i can finally reach a door where 3 invincible enemies i cannot tell how and where i have to go to remove their unlimited health, i see a door leading to the 88, but smoke? it doesn't keep them from shooting me i get behind a tree and somehow a guy in the upper stairs of the house facing the backyard all ways spawns and shoots my ass whenever i try to rest behind the tree. 
 
and i've noticed they all of a sudden start doing more damage back there, on veteran a gweher would take 3 shots to kill me, these guys take 1 using the same gun.