Mediocre. Sure it's a 5 mana 4/6 restore 5 Health to your hero with Lava Burst at best in Standard, and Shaman isn't really the class that struggles with healing *cough* Healing Wave *cough* Couldve been like a Rare instead tbh.
EDIT: Could actually be decent with board clears. Still expensive and conditional, though. Like 8 mana 5/1 Overload (3) "fully heal your hero and clear the board" sounds good but VERY conditional.
It has pretty good stats for a 5 drop, but there's already a lot of 5 drop minions in the game that have good stats and effects, even with Naxx and GvG being removed. Thing is, you can't really play this on turn 5 unless we're getting some sort of 0 cost burn spell, which makes this bare minimum a turn 6 play with something along the lines of lightning bolt. Still, that's decent for a turn 6, and I could see this getting some sort of play, but sadly more healing is not what Shaman needed.