PVE.
Disc is quite wrong. The way it heals, it simply doesn´t feel like a healer.
First of all, there is 0 amount of skill involved. You simply need to learn and understand your spec mechanics and apply them. Simple as that.
Holy, on the other hand, has a large arsenal of spells which you are free to use whenever you want and as you wish, you do not have to follow a strict mechanic gameplay to make it work like you do with Discipline.
Now, don´t take m wrong, I love both, but it feels silly to see all the new priests going Disc and saying "oh it takes skills unlike holy"... /facepalm.
As holy you have freedom of spell you, which means that to be a GOOD healer, not just ok, you must know the fight details, know when exactly the damage is coming and get the appropriate spell ready. Sure, the same can go for Discipline, but the difference is that you can not freely make a difference, you simply follow a "rotation", or call it as you wish.. you trigger mechanics. Holy strictly relies on YOUR time/action decisions, which come at a cost if you use the wrong spells as they might be on a CD when you really need them.
Being in a raid a few hours ago, we were struggling for raid healing, we literally had no raid healer able players. The one priest we had was a discipline and of course he could never get us to even 70%... Holy, meanwhile, not only would take care of the tanks but it would also top up the raid in no time with the proper set of skills in play.
What´s you view?
Do you like a traditional, strong, capable of any healing style (BUT the one you nee to actually think) or a modern DPS support/passive healer where you just need to make sure you keep up the mechanics to heal?
To be honest, I would expect new priests to embrace both specs and KNOW when each is best to use... not just stick to one.