You mean the huge buff to a skill that is extremely hard to use, very punishing when you screw it up, and that means any boss/mechanics movement will make your DPS tank down to nothing for a good minute and a half, at least? It can only be used in raids too, it's useless in M+. They also cut down massively on the AoE it once did, anyway.
The thing is, Arms is already ahead by a lot, the only time Arms ever lost to Frost was on long 2-target cleave fights or in big sustained AoE, and even then, not by much. Any time it involved long single target phases, Arms would come out ahead by a good 15-20%. Arms is getting a flat blanket buff, on top of one of the best tier sets in this upcoming raid. Frost is going to still be good at what it was, which is sustained AoE damage, but to say that DK is in a better state than Warrior (which is what the first guy I answered to was saying) is simply not true, and could only be coming from someone that hasn't played a DK in this expansion.
And this is speaking of DPS alone, not even factoring in that Frost has the worst movement in the game and very reduced utility, the only unique thing they bring is Grip that doesn't even work at all on raids for the most part. Brez is nice and all, but it's not even close to unique, and you almost always have at least another 2 or 3 in the raid. A temporary 10% HP buff for the entire raid is far more useful than the grip would ever be. If they gave Gorefiend's Grasp back to the DPS specs as a talent, maybe we'd have a case, but not in the current state.