The way the class is designed now, is that every single heal has a place. There is no "shockadin". Holy Shock is used by all holy pallies. How much you use it depends on your own play style. Personally, I feel like holy shock should be a staple. You don't need to use any specific spec, simply get Daybreak, and put points into Crusade as you level to 85.
But don't think that holy shock is a good dps spell. It is ok, but it is primarily a heal.