Personally, I've been testing it in Expanded. I use Zygarde/Landorus to attack for the first turn or two, then Ninja Boy out the EX, put in Croagunk, and immediately evolve into Toxicroak. Also in Expanded, you get Laser and Virbank, which allows you to hit for 100(Attack(50)+LaserBank(30)+Muscle Band(20)=100) before Strong Energy. The problem I've seen is that Darkrai DEX and Keldeo cripple this deck, unless you can knock them out. Pretty much every deck runs one of the two.
In Standard, with Zygarde/Ninja Boy and Ariados/Chaos Tower or Zoroark or Whatever could see some results. From my testing, I've seen a lot of people dropping Hex Maniac recently in favor of Pokemon Ranger(I really don't know why but oh well). This is one of those decks that can't become the best because it's easy to counter. Personally, I think that it's overhyped.