I just noticed on the PTR that the new Holy Shock:
a) costs 650 mana (up from 435, a ~33% increase), so that’s a big cost increase and makes Holy Shock much more of an “emergency stopgap” heal than a viable part of a healing rotation. This is also going to make life more mana-intensive for shockadins, unfortunately. Blizzard giveth and Blizzard taketh away.
b) is currently bugged and doesn’t consume Divine Favor when DF’s activated – you get a constant string of crit Holy Shocks until you cast FoL or HL to use up the DF charge. I assume that will be fixed before it goes live, though.