In multiplayer, people rarely realize how useful needlers can be. Using one in the open usually isn't effective, especially against strafing targets. However, when your target is in a narrow hallway or catwalk, needlers can decimate them. Jumping is ineffective in evading needles.
Using dual needlers is even more devastating. You can fill an unaware sniper full of needles before he even has time to react. When locked on, it is more accurate than the SMG. Dual needlers reload just as fast whether or not you are dual wielding them.
It does have drawbacks, though. Targets moving from side to side can evade needles, and needlers are useless at long range, as the needles have a limited lifespan before detonating.
To kill your target you will need to fill it with enough needles for two detonations to take place, but this shouldn't be hard when dual-wielding.