I'm really hoping that one ends up proving to be equal in terms of damage output that Nidoking had in Gen 5. I don't care if its physical or special, as long as its a set that does comparable damage. Nidoking, surprisingly catches people unawares, so long as one isn't stupid enough to run it against something obviously faster.Nidoking is not making OU any time soon-- it's too frail, too slow, and too many exploitable weaknesses. The slight bump to its ATK will keep people on their toes though, and Poison Jab could see new use with all the fairies running around.
For the most part, overall people are right that a 10 point boost to ATK isn't going to stop Special Nido from being almost completely better.
I know I've had good experience running Nidoking as a fast special sweeper. I've gotten the drop on many dragons and heatrans with him and I'm hoping to continue using him in Gen 6