I've been messing around with the beta. I haven't had too much of a chance to deal with Arcane yet, but I've toyed around with Fire and Frost.
Oh ho ho, as much as I love frost, I'm going to have to let it go. Frost just doesn't seem to have the style that it did in BC; the damage isn't as much as I'd like, and the nerf to spell power is pretty freaking sad. I was sitting with 1100+ unbuffed spell damage, now, it's at something like 900. Not good.
FIRE
Dear lord, THIS is what it's all about. Living Bomb is basically a mage version of SoC; and on top of that, you get a talent that makes it so that after a Blast Wave and/or Dragon's Breath, Flamestrike is INSTANT. Extreme burst damage capabilities.
I'm going to have to toy around with arcane to let you know the finer details, but all in all, as much fun as the "New" fire has been, I'm afraid that if the current trend continues, I might just have to retire the mage; the damage output isn't nearly what it was, and I'm very upset with it. Don't let the pretty new talents get your hopes up kids; hopefully Blizz will fix a great deal of the issues with it; I can only pray that they will.