Good reward - almost Justicar-level upgrade that also gives a minion an almost BoK - but healing 15 health is a lot, so while you could technically complete the quest at some point without ever building a deck dedicated to the quest, you'll more likely need to include some cards that help you reach that target. Given that healing your opponent's stuff counts, Wild Pyro/Northshire Cleric/Circle of Healing, could be important, and we could even see a resurgence of Injured Blademaster. Reborn minions, of course, may also be viable given that as far as we know they return damaged down to 1 health (rather than having their health set at 1), so can be healed up from that.
Given that it's not super easy to hit in a timely manner I'll wait until we can really start testing it out to see if it fulfills its potential, but a hero power that essentially gives a minion +3/+6 in ideal circumstances is amazing, and even just +3/+3 is great.
Zoo decks really don't want to skip turn 1, especially the ones with Grandmummy and Extra Arms. Maybe it could go into a more midrange priest, the kind that wants to turn 3 blademaster into turn 4 Psychopomp.