It's great after the patch, I drew up a pros/cons list.
Pros: -Able to take a Shotgun Secondary without Overkill -Faster Knife Speed -Tighter Hip Spread than all Non-KSG Shotguns -Tactical Knife and/or Dual Wield are both very effective.
Cons: -Slightly lower range than other shotguns. -Smaller Capacity -Shell by Shell reload unless using fast mags.
Due to this list, I think that you'll have the upper hand over S12/M1216 users due to the tight spread, and will do better in 1v1 fights. However, you'll suffer against groups. I made a class with it recently, and I've been doing well with it:
Executioner w/ Laser Sight Tomahawk Concussion x2 Lightweight Fast Hands Ex. Con and Dexterity
This is a great class for CQB maps (e.g 90% of the maps), and when you run out of ammo, you still have a rather effective Knife-Only build. Plus with the Laser Sight, you've got a tighter Hip Spread than the SMGs and as tight as the KSG with a Laser. It's amazing.
One of the proud people that still plays Mirror's Edge to this day. Not changing my sig until DICE officially announces Mirror's Edge 2