It rocks, I understand this is probably not everyone's cup of tea but this mode has revitalized the game for a group of friends and I.
I honestly hope they keep some sort of super hardcore mode on rotation for as long as possible. The one shoot kill mechanic is amazing.
I do have to point out the AI will still shoot through walls wall-banging you at an unrealistically high rate, regardless of whether you move or go prone.
I have also found a couple of instances where the enemy were actually invisible ( a friend could see them but I couldn't).
And, they will sometimes start shooting through smoke right before it clears up on your own screen.
So at the end of the day, the AI is the only aspect that really needs attention.