I like the new masteries overall, but...
...I don't like how in the cunning tree, I have to choose between having extra mana regen or having the bonus damage to 40% HP or less targets. Both are very important to mages, and having to choose is kind of hard, and especially with the mana potion removal, not having the mana regen sucks. Additionally, choosing between the extra CDR cap or having penetration also sucks for the cunning tree, since both are important. Finally, the resolve tree makes you choose between having extra HP or having sustain, which is a tough pick for champions like Zac.