1. Motion sensor in BC2 was balanced. THey had three, but they had a time limit to each one. You had to be smart, not lazy, and had to have waaaaay more situational awareness.
The perpetual motion sensor in this game is the worst. Terrible.
Also, everything should have a countermeasure. You should be able to bypass any motion sensor the same way you can bypass a claymore or at least with a specific camo.
2. The proxy sensor on the vehicles is lamer now too. In BC2 you could just hold still. Now it picks everything up weather your still or not. Terrible. Bad for the game.
3. The speed in which you can drop to prone as compared to the speed of getting back up. If you drop to the ground that flat in reality it would hurt. If you drop that fast in the game you should take a tiny amount of damage, or at least make it slower. All the idiotic drop shooting going on is terrible. You're going to run away from me, while I'm shooting you, drop flat and spin fast enough to then aim and kill me? No way.
4. You shouldn't be able to morph 75% of your body into a wall or corner, just leaving a tiny part of you sticking out that barely resembles an enemy. Such a cheap thing to exploit, but it's rampant as hell. At least in BC2 you couldn't go prone and pull that nonsense.