Now that we've had all the class blogs, I'm going to go a bit more in-depth on the specs that I play the most.
I've tanked as Protection since I first started doing things that weren't solo questing, way back in Burning Crusade. I spent a bit of time terrible (not using Holy Shield, which was absolutely core to the spec in BC) and then figured out how to play decently. In Wrath I started raiding, and I'd say I got actually pretty good.
In Wrath of the Lich King, Prot Paladins had something called the "969" rotation. Single-target or AoE, you'd always use five abilities, essentially alternating between a two-ability rotation and a three-ability rotation. Shield of Righteousness and Hammer of the Righteous were both on six-second cooldowns, so you'd alternate between them. Then, you'd have Holy Shield, Consecration, and Judgment essentially every 9 seconds, weaving them between the 6-second abilities (I may have swapped Judgment and Shield of Righteousness - it's been a while since Wrath.)
It worked out - you had a bunch of buttons to press - but it was very, very simplistic.
Queue Holy Power, which came with Cataclysm. Prot would now build up to a big Shield of the Righteous (note the subtle name change) and had a little less predictability in the form of things like Grand Crusader. Consecration also got a longer cooldown and cost a ton of mana, so you couldn't maintain it at all times, but let us never speak of that dark time again.
The thing is, before Cataclysm, there was a weird way in which Paladins' lack of structure (I'm also talking about Ret here) oddly locked them into a much stricter structure. Because all these abilities were just based on cooldowns, you had to hit them right as they came up and you couldn't fit in things like Avenger's Shield - which back then was used only for pulling.
Abilities have still been based on cooldowns, which has made Protection (and Ret) still a bit reliant on a lockstep rotation. But there's been a bit more randomness and unpredictability to keep you on your toes. The addition of two extra Holy Power slots in Mists really made the mechanic a lot more interesting, as you could choose to bank that HoPo so you could save up your defensive ShotR for some big hit and not waste Holy Power.
Ultimately, I don't think that the rhythm of the Protection Paladin is going to be all that different - we'll probably be able to raise our shield about the same amount of the time. Light of the Protector strikes me as probably being weaker than a 5-bastion Word of Glory, but you won't need the build-up anymore.
Still, I don't know if simply having a cooldown that ticks away is as cool as a resource that we generate. In the end, it might wind up accomplishing the same thing - we'll bank ShotR charges like we bank Holy Power now - but it feels a little more passive.
The other thing is AoE. I like that Hammer of the Righteous will simply replace Crusader Strike for us - frees up a button, after all, and as tanks, it really has to be a single-target fight for us to use CS - but I really do not like the idea that it only gets its AoE capabilities when you're standing in Consecration. Tanks needs easier AoE - they always have to put a little threat on every enemy to keep the healers from getting eaten. I don't really see why they can't just let HotR work the way it does now and give us some "free" AoE like Monks get with Keg Smash, Warriors get with Revenge, Druids get with Thrash, and Death Knights get with Blood Boil (though to be fair to DKs, they're going to focus more on Blood Strike, which has a similar AoE preparation requirement - but they still get Blood Boil for burst AoE.)
I suspect we're going to see some iteration on this design through the beta. At the moment, Prot doesn't really have any sort of resource to track. I'm kind of surprised that we're seeing DPS shamans, Shadow Priests and Balance Druids get a non-Mana resource but we aren't seeing Paladins get one.