Spells:
Righteous Defense
Come to the defense of a friendly target, commanding up to 3 enemies attacking the target to attack the Paladin instead.
The AoE taunt. Looks solid. Pretty good for our role of "protectors of the cloth". If you enable Target-of-Target, it will be trivial to use to taunt a specific mob as well.
Seal of Justice - Rank 2
Fills the Paladin with the spirit of justice for 30 sec, giving each melee attack a chance to stun for 2 sec. Only one Seal can be active on the Paladin at any one time.
Unleashing this Seal's energy will judge an enemy for 10 sec, preventing them from fleeing and limiting their movement speed. Your melee strikes will refresh the spell's duration. Only one Judgement per Paladin can be active at any one time.
The new Seal of Justice depends a great deal on what "limiting their movement speed" means. If it's an out and out reduction in speed, like Hamstring, this is a great boost. However, it's also possible that it just means that you can't use speed boost abilities to increase your speed past 100%. In that case, it's a small boost, but may be useful with your own permanent speed increases like Pursuit of Justice. Hopefully the side effect of being immune to Fear while affected by Judgement of Justice has been removed.
Talents
Stoicism
Increases your resistance to Stun effects by an additional 10% and reduces the chance your spells will be dispelled by an additional 30%.
This is a decent 2pt PvP talent. Nothing amazing, but the anti-dispel is nice as purge-happy shamans are annoying.
Improved Resistance Auras
Your Resistance Auras also reduce all spell damage taken by an additional 5%.
This is an all-star talent. 2pts for 5% less damage is really good.
Improved Divine Shield
Reduces the cooldown of your Divine Shield spell by 1 min and reduces the attack speed penalty by 100%.
LOL. Sometimes, I love Blizzard. Everyone complains about paladin bubbles, so they give us a talent that makes them even better. Again, much more useful in PvP than PvE.
Ardent Defender
When you have less than 20% health, all damage taken is reduced by 50%.
Now this is an intriguing talent. The paladin boards seem to disdain this talent, but I think it may be good for tanking. The key to this talent is to ask, if I am tanking, when will I be at less than 20% health?
Given that most bosses do steady dps and additional spike damage in the form of special abilities, if you drop to less than 20% health, it probably means that you were just critted by a special ability. In that case, Redoubt will proc and combined with Holy Shield, means that you probably push criticals off the combat table, meaning the next few attacks will not crit. So blocks and half damage should be enough to buy your healers the few seconds they need to complete their big heals.
However, I'm not really sure how this will work in actual play, and it will be very interesting to watch. In PvP, I don't think it will help all that much. It might buy you one or two seconds, but I don't think it will be worth the 5 points for a primary PvP'er, give that you might get dropped from 30% to 0% quite easily, and this talent will do nothing to help.
Weapon Expertise
Increases your weapon skill with all weapons by 10.
Decent talent. Reduces the number of glancing blows and misses against end-game bosses, which will help a lot in generating threat. Again, mainly PvE.
Avenger's Shield
Hurls a holy shield at the enemy, dealing 270 to 330 Holy damage, dazing them and then jumping to nearby enemies. Affects 3 total targets.
The Captain America move! If this talent has a half-way decent animation, I am probably going to spec Protection. This is everything a 41-point talent should be. Fun, unique, and stylish. And it dazes people! Which means you use it to slow runners.
Actually, let's be honest, I'm going to be using this whenever the cooldown is up. About the only downside is that you can't use it to pull. Although you are a Protection Paladin, so pulling 3 mobs at a time isn't that big a deal.
My final verdict is that the new Protection tree is very good. The mid-level has been fleshed out with useful talents, and the end talents are solid. Plus you get to throw your shield at people! The only real downside is that the first tier of Protection is still a little lackluster, especially compared to Holy or Retribution.