This gun is probably going to get nerfed in the first patch since it's time to kill is ridiculous. There is no reason whatsoever to use an SMG or shotgun or any other weapon in CQB and mid-range when this gun can get 10 kills in 1 clip. The one weakness is targets at range, but even then a foregrip gets rid of that problem for the most part. Enjoy it while it lasts!
We'll see... I kind of doubt anything is coming for the snipers... yet. Snipers haven't been too prevalent in the 20 hours or so I've logged. The MSBS on the other hand is by far the most commonly used weapon I see now. Whenever they do nerf it, it will go from being a beast to totally useless since if it's not a 1 burst kill up close, you'll just be dead from any other weapon in the game. If they buffed health, though, it might be more balanced since you'd have time to get off 2 bursts. Seriously doubt a health buff will happen.
The gun is incredibly latency based with how it look like it kills you. I'm not denying that there is mad bullet mag or aim assist.
The gun only requires 2 of its bullets to actually 1 hit you with good latency, which makes it worse. I like to compare it to the M16 in MWF2 because that was the balanced version of a 3 round burst gun. You had to have holo, you had to have stopping, and you had to make sure all rounds hit. With the MSBS you need nothing, show up to the game and you'll drop 1 shots.