"Stack intellect." All you had to do was ask any question about holy paladins in Wrath, and you'd receive that infamous answer. Intellect was the solution to all of our problems, and it was through intellect that we conquered our corner of the healing game. Intellect allowed us to cast indefinitely without ever running our mana wells dry, and intellect allowed us to cast our most powerful heal without even a moment's pause. It was a matter of fact. Holy paladins would simply overheal in massive amounts, and nobody cared.
I suppose intellect was only half of the problem. Holy Light clearly scaled too well as our gear improved. It was meant to be expensive but powerful, a necessary evil for dire situations. Once the scare of running out of mana was debunked, there was no reason not to use the most potent tool in our arsenal. While the developers may still blame the imbalances in Icecrown Citadel on the extra tiers of gear they had to add to accommodate heroic raid encounters, when an errant DPS class' performance scaled out of control, they were quickly reined in. Holy paladins' power was left unchecked because we were merely healers. The hammer would drop on us in Cataclysm, anyway.
The intellect train continues to roll
Instead, intellect has become even more important in Cataclysm. Not only does it grant us all of its previous benefits, it is now our major source of spellpower. Now that holy paladin heals are not capable of healing any target from empty to full in one cast, spellpower actually becomes very important in ensuring that we're able to accomplish our goals. More spellpower means we'll need fewer casts to top everyone off, which in turn reduces our mana expenditures. We're going to stack Brilliant Inferno Rubies, and any enchant or buff that provides intellect is going to be incredibly important for us.
Spirit and intellect are intertwined
The formula for mana regeneration has been edited and revised several times since its original introduction. The latest round of changes removed the previous "five second rule" from the game entirely, and the removal of the MP5 stat resulted in the unification of regeneration across the board. Since only healers will utilize spirit for its regenerative properties, every healer was also granted a form of the Meditation effect. The result is that we regenerate at half power in combat and full power when out of combat.
What many people don't know is that the mana regeneration you receive from spirit actually scales with the amount of total mana you have. Because having more mana means you get more regeneration from spirit, stacking intellect actually increases the potency of any spirit we happen to have; thus, the spirit-intellect relationship is born. More intellect means more powerful spirit, and more spirit means more powerful intellect. While this may be old hat to priests and druids, holy paladins have never utilized spirit before. We were previously tethered to MP5, which neither scaled nor varied in potency when in or out of combat.
Spirit rides shotgun
With only four secondary stats available for use on holy paladin gear, we really don't have that many possible gear combos. Critical strike chance is pretty awful for us at the moment, and I don't see it being sought after at all. With just spirit, haste, and mastery to put on our gear, it's clear that we're going to see a lot of spirit. Of the three valuable stats, it's the only one that helps us regenerate mana. In fact, haste actually results in us spending more mana over the same period of time, while mastery only serves to give tanks a small health buffer. In any sort of encounter that requires healer longevity, spirit is going to be key to maintaining the level of mana regeneration required to survive.
Haste will likely be our first priority after spirit, meaning that haste/spirit gear is going to become the most valuable gear we can acquire. The reason that haste is so crucial is that we'll want to get back to the haste soft cap to lower our GCD to one second. This is incredibly similar to the intellect-stacking, haste/MP5-wearing days of Wrath, and it seems like we simply traded MP5 for spirit. Mana regeneration and caster gearing efficiency are both concepts that have already been solved. The new healing paradigm of multiple heals of varying power and cost is going to be the biggest change for us in Cataclysm.
Gearing in Cataclysm is basically identical to gearing in Wrath. We'll focus on acquiring as much intellect as possible via gear, gems, and enchants, and we'll favor spirit for regeneration and haste for throughput as our secondary stats. Critical strike rating will be around, but only as a stat on non-ideal gear, while mastery's potency remains to be seen. I wasn't terribly impressed with mastery's effectiveness on the beta, but that may be due to the fact that many combat parsers were unable to handle the new spell properly.
The Light and How to Swing It (Holy Edition) helps holy paladins become the powerful healers we're destined to be. Learn the ropes in Holy 101. We can help you keep a tank alive, heal a raid when necessary and beat the global cooldown. Tanking is a job, DPS is a craft -- but healing is truly an art.