If this "low-carb" Coke is or leads to Diet Classic Coke, this is great news and it's long overdue.
I prefer regular Coke to regular Pepsi, but much prefer diet Pepsi to diet Coke. Diet Coke has no "bite" for lack of a better word, and it does have an aftertaste. Diet Pepsi probably has an aftertaste too, but I don't notice it.