Honestly, it's another spray and pray n00b weapon. Thankfully it has piss poor range unlike the Striker in MW3. But that really isn't a big deal since the maps are so small. I've never been a fan of semi-auto and full auto shotties, I feel they're just too easy to use
the S12 can take down 5 guys ''easily'' all in the same crowd compared to ANY rifle, smg, ballista or whatever
I would pay to see someone take out 5 guys with one clip of an AR standard mag (no lining people up for headshots either). SMGs would be tough too, the fact is non pump action shotties have are the easiest to use because they can kill multiple targets faster than any other weapon in the game. Normally that's countered by being vulnerable at range but Black Ops II doesn't have any range to it's maps
It has piss poor range and a piss poor damage profile; the Remington is a vastly superior shotgun in every way. And I say this as someone who has already grinded out the gold camo on the S-12.
As far as taking out 5 enemies in one room, maybe on a LAN connection or against players who are completely oblivious to everything happening around them. In practical use on multiplayer, I found it next to impossible to take out even 3 tightly spaced targets; you'll usually drop the first one pretty easily and then it's hit marker city until someone turns around and kills you with an SMG or pistol. There's simply no consistency to the way it does damage...I got my 250 one-shots & then some, but it took forever and I'd just as often get multiple hit markers on an enemy standing right next to me. Now I'm working on the Remington's camo & it is immensely easier to use and far more consistent with one shot kills at close range. I was incredibly thankful when I finally tallied my last bloodthirsty so I could put the S-12 away forever.