If anything, arcane mages are worse than ret. Pallys at least you can run away from. Arcane mages can do just as much damage just as quick, but from 36 yards away. And if you gang up on them, they just frostnova > manashield > blink > iceblock > instant invis. Good luck killing one with less than 3 people. If it's one vs one, all they do is cast one dmg spell and finish you off with instant casts. Used to be in a 1vs1 fight they at least had to fight tactically to win against my boomkin, using things like spell-steal to take my heals, blinks to get out of roots, etc. Now they just hit dmg spells because they don't need anything else. They can kill most anyone quick enough that they won't take enough dmg to even get through manashield.
Don't take this as a whine post though, I'm definitely enjoying the changes overall, and they've already said (blue posts on official forums) that they're not nerfing anything until the exp comes out, so we know how things really work after they re-itemize and players get to 80, etc. Which I definitely think is the right move to make. Last expansion, same thing happened with ret pallies getting OP in the patch before, except they nerfed them to the ground just before the exp then, and they were useless after. Never played a pally myself so it didn't affect me personally, but it's still not cool at all.