Though I can't seem to find the original comment made by Honorshammer, he made a interesting comment about why he does not like to heal as a Paladin. He made the claim that Paladin healing is boring (I'm summarizing. I don't believe he used the exact word boring) since all Paladin's do is spam Flash of Light on the tank and cast the occasional Holy Light to recover from burst damage. I feel that this view of Paladin healing, while not completely baseless, is more of a stereotype than a reality, and I'd like to give you, the reader, my two cents on Paladin healing.
Disclamer: While Paladins only have two viable healing spells, there are a wide variety of schools of thought pertaining to Paladin healing and what stats and spells to focus on. The views expressed in this post only reflect the views of the author and are not the end all be all of Paladin healing.
Paladin Healing Acronym Primer:
FoL - Flash of Light (Seven ranks total, though only the max rank is commonly used. When I type FoL it refers to the max rank.)
HL - Holy Light (11 ranks total, and ranks 4-11 are all used depending on a Paladin's style.)
HS - Holy Shock (Five ranks total, though only the max rank is used. Due to it's cooldown, high mana cost, and short range, HS is only used in rare circumstances where the tank must be healed immediately or he will die.)
HPS - Healing per Second
The important thing to know about Paladin healing is that we do cast FoL. We cast it a lot. The main reason for this is the FoL is very efficient and provides a great deal of healing per mana. By chain casting FoL on a tank who is taking consistent damage, Paladins can keep him up for a long time, and almost indefinably if a Shadow Priest or Restoration Shaman is in our group (due to the extra mp5 they grant us). The main problem with that statement, however, is that in most fights tanks take anything but consistent damage. Thats where HL comes in. While not as efficient as FoL, HL provides much more HPS and lets you get your tank back up to full faster.
That was the simple explanation of Paladin healing. The complicated part requires discussion of an interesting Paladin talent called Light's Grace. As you can see in the tooltip, Light's Grace shortens the cast time of HL from 2.5 seconds to two seconds, which, as any healer can tell you, can be the difference between downing a boss and your tank splattered all over the floor. All Paladins, regardless of their methods, should keep Light's Grace up at all times. This allows you to drop a big heal like HL11 .5 seconds faster. Most FoL spamming Paladins use either HL4 or HL5 ever 10 seconds or so to keep Light's Grace up, and otherwise use FoL.
Down ranking HL is also an important part of Paladin healing. If my FoL can't keep up with incoming damage, I tend to throw a few HL9 into the mix, which not only brings the tank's health back up, but keeps Light's Grace up as well.
Overall, Paladin healing is not just FoL spam, but rather is a delicate balance between efficiency and keeping your tank alive. Paladin healers must be aware of their surroundings and know the ideal spell to cast in order to maximize efficiency while minimizing overheal and keeping the raid topped off.
As a final note, for any new or learning Holy Paladins out there, always value keeping the tank up over efficiency (something I had to learn as well). Your tank doesn't care that you are at 50% mana nine minutes into a fight if he's staring at the spirit healer.
For the Horde and the Naaru!
What do I cast?
HL11 with Divine Favor: My, "Oh shit!" heal
HL1: Cast right before a pull to get Light's Grace going