I don't know what it is that disappoints me so much about MW3.
The damage to health ratio is so unbalanced, every weapon kills in 2-3 shots and fires so fast, hitscan, in close quarters. Confrontations are just too fugging fast.
There is just so little to the gameplay. How EVERYONE has 100hp, and more than that they RELIABLY have 100hp thanks to the oh-so-quick health recharge makes every encounter almost identical. There is no trade off between mobility and health or other special attributes as in other games.
See, the health in Team Fortress 2 may be more "primitive" with health packs and medic healing, but it adds another layer to the gameplay and strategy. Like how you have to trade off standing your ground or going to find health, you still usually have enough health with even 60% gone to stand a fighting chance in combat. There is the strategy in targeting those you reckon have the lowest health, also based on their very distinctive classes.
You have such huge difference in roles and mobility of classes. Demo and Soldier are slow but can make a few huge jumps with rocket or sticky-bomb jumps at cost of health. Scout is very fast and can make very long jumps very often. Pyro is quite fast but has anti-mobility of the air-blast (most of the time), Heavy is slow as hell but a real tank, huge health and such a deadly gun. Engineer, sniper and spy all have pretty average speed but such unique roles with TOTALLY different playstyles.
Thing is, I always feel like I am a sniper in CoD. I might have a relatively slow firing single-hit-kill sniper rifle, or I might have one that is full auto and kills in a few bullets. You have to really go shotgun or sniper to have really distinct gameplay with hipfiring, but again the damage:health ratio is so high and you move so slow that encounters are just over in a flash of spraying bullets at each other. Over and over it is jog-jog-jog Aim-down-sights + shoot.
They'll never do the grenades right. Overpowered as single shot, then they nerf them to be weak yet you still have only 2-3 rounds slow-firing = worthless. Grenades are weak in TF2 and Tribes, but you can launch a ton of them!
And then there is the general direction-less-ness of the gameplay in CoD. So much camping. Such predictable objectives. I you've played one match you've played them all. They all just blur together like Groundhog day.