Originally Posted by
Danner
As of patch 4.2, Disc is generally superior in all raiding situations.
If you ever have a choice, Disc will make any content easier and safer.
Some fights are downright impossible as Holy unless everyone is overgearing it.
And you won't really be getting much gear from the Firelands as a holypriest anyway.
But for normalmodes and 25mans, Holy is still a viable healer. You just won't excel as one.
As of patch 4.3, things are changing.
Holy is getting a significant buff in Divine Hymn, offering a raidwide cooldown. It will be needed in 4.3.
Spirit cloth is again available from raidbosses, meaning you actually have a business raiding.
Druids are no longer so overpowered that holypriests and shammies are invalidated.
And the fights are somewhat designed with shammies and holypriests in mind - they fit our heals rather than only fitting druids.
This is definitively reviving the spec as far as I can see, and Holypriests looks to be a strong raiding spec.
At the same time, Disc remains a stong raiding spec. So in 4.3, it shouldn't really matter which spec you use.
Then again, noone really knows how the 4.3 hardmodes will play out, so it's hard to say for sure.