I am kinda disappointed from the mage cards. I can see Polymorph:Boar working in an aggro deck. Arcane Blast looks good, but i still don't know if a spell power deck would be viable. I like Flame Lance also and would likely replace 1x Polymorph in the decks who run it, not that huge of an improvement though. On the fence about Coldarra Drake and Fallen Hero. Dalaran Aspirant is nothing to write home about, Effigy is interesting, but also RNG dependent. Not sure how it'll compare to Mirror Entity. Spellslinger also another RNG card that might hurt you more than help you in certain matchups. Rhonin is trash and just too slow. What i've wanted to see was a card than could enable a finishing combo, but it's not there. Just more removal and it's not what the class needed.
From the rogue cards, Anub'arak, Beneath the Grounds, Cutpurse and Poisoned Blade are terrible. Burgle, Shado-Pan Cavalry and Undercity Valiant are average and average cards don't make it in good decks. The ones i like are Shady Dealer and Buccaneer, pirate rogue might become a real thing.
EDIT: Just stating preliminary opinions, there are always surprises and i might be wrong on some of the those cards.