New Unleash the Hounds feels so stupid. I'm only rank 14 in constructed, but I literally tossed a deck together in ~3 minutes and it hasn't lost a game yet. Buzzard+UtH means you don't run out of steam, Timber Wolf+UtH gives lots of damage out of nowhere, and Kill Commands give reach. It doesn't even use any rares and it feels way too strong.
Also, for some reason, I can only play Paladin in arena. I feel like Mage, Shaman, and Warrior should be really good, but I'm nowhere near as consistent with them, often getting <= 4 wins. With Paladin, I usually get at least 5 wins. My guess is that Paladin has a lot of good 4 costs, which I'm starting to see as the key cost point when building an arena deck. You want 2 and 3 costs for early game, but 4 costs change the board so much more.