How holy power actually works
Holy power works mechanically like a stacking buff. Right now, we're able to stack up to 3 holy power points (HPP). The HPP buff has a 30-second duration. Any new holy power generator (HPG) that we use will both add a point to the stack and refresh the duration of the stack to 30 seconds. This is nearly identical to how Serendipity works for holy priests, if you're familiar with that mechanic. You can right-click off your holy power stack if you like, though I can't think of a good reason to. While I'm not ruling out the possibility of Blizzard introducing a new bar to display holy power points, it's likely that a mod like Power Auras will be our best bet for monitoring our HPP.
Holy power is generated when we cast certain spells, or when we use Tower of Radiance. For holy paladins, we'll be seeing most of our holy power points coming from Holy Shock. Right now, Holy Shock is healing for nearly as much as a critical Holy Light, yet for a surprisingly low mana cost and an instant cast time. As I mentioned previously, Holy Shock is going to become our go-to heal, which we'll be using on cooldown. We'll be seeing a HPP ever few seconds from Holy Shock alone, though there are a few other ways for us to pick up HPP.
If we're in the mood to DPS, we can use Crusader Strike to smite our enemies and generate an extra HPP while we're at it. I tried healing a few 5-man dungeons while standing in melee range and using Crusader Strike, and it felt like I just didn't have enough spare time to use CS regularly enough. Our other option for generating HPP is to use a direct heal onto our Beacon of Light target, via Tower of Radiance. Any heal will do, and Holy Shock will actually generate two HPP when cast on the Beacon target.
Word of Glory: exploit or intended?
What's more interesting is that our holy power release (HPR), Word of Glory, will generate a HPP when used on the Beacon target. Because WoG can be used with just 1 HPP, you can actually cast as many WoGs as you want onto the Beacon target by just spamming WoG. It's an instant, mana-free heal that can be spammed while moving. Unfortunately, using WoG with just 1 HPP is pretty weak, though it's nice to know we can throw some heals onto a tank no matter how much we're moving. I would kill for something like this on Halion's twilight phase. I'm not sure if WoG generating a HPP via Tower of Radiance is intended, but we'll see if Blizzard nerfs it or not.
Speaking of Word of Glory, it's going to be holy's primary HPR. At one stack of holy power, it's pretty weak. At three stacks, it's actually quite potent, healing for around the same amount as my Holy Shock. I had a hard time remembering to use it as I was healing dungeons, though I suspect it'll be easier once I can get an addon to alert me when I have a 3-stack of HPP ready to unleash as a Word of Glory. It's a bit weird having so many new heals to use, especially when trying to break my mind out of the Holy Light spam mindset. Right now, I basically use Divine Light like Holy Light today, and Holy Light like Flash of Light today.
The only other holy power release available to holy paladins is Inquisition, which I tried out but wasn't really impressed with. I just wasn't doing enough damage, even while leveling by myself. I even picked up Denounce, which grants instant Exorcisms after a crit, but even then my damage was too weak. It looks like Word of Glory is really going to be the HPR of choice for holy paladins, though its current strength has me wondering exactly how useful it will be. I imagine that it will be our go-to button for situations where a target is low on life but Holy Shock is on cooldown, especially with the Last Word talent buffing its crit chance by 60 percent on targets with low life. While it may not become part of our normal healing rotation, it's nice to have a clutch instant cast to fall back on in times of need.
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.