My take:
Quest shaman is really highrolly now. It was often taking ages (aka 8-9 turns) to finish the quest. One extra overload might not sound like much, but even before you could desperatelly wait for overload for 2-3 turns, now it can be even longer. Perpetual… I would say OK nerf, was strong, will be strong. Just more fair.
Quest Warlock is hit hard. I would say this will drop it to T3. It takes 4 hero powers instead of 3 to finish first one. That is big - it takes longer, you might need extra 1 mana for giants. Not even talking about weapon, which will be kinda dead. You cant coin-weapon-backfire into mass discount, which will make it much weaker to any fast deck.
DH - it will be fine. It was 1 in 10 autowin turn 3-4, now it will be 1 in 20. Nothing really changed, it should have been nerfed by 1 card drawn in 1st questline.
Illucia is dead… I liked the card in control, when you could disrupt OTKs… This aggro priest just killed the control, which could counter OTKs somehow.
Buffs:
Beast hunter - still unreliable.
HP Mage - I will try it, but dont think it will be any good, sadly. autolose to any questmage.
Quest Warrior - significant buff, I think it can move the class into T2…? Still will suffer, as the quest reward is not so rewarding as others permanent rewards.