HDL

    * Divine Spirit – this spell is now a core ability available to all priests.
    * Discipline has access to a new talent, Power Word: Barrier. (Think of it as Power Word: Shield for your whole group).
    * Several area of effect (AOE) heal spells have been improved: Prayer of Healing can be cast on any groups in your raid party. Holy Nova's mana cost has been reduced. Circle of Healing now heals for more.
    * Shadow priest PvP survivability has been improved: Shadow Form now reduces magic as well as physical damage. Dispersion now removes snares.
    * Penance – this spell can now be targeted on the priest.
    * Serendipity – this talent now reduces the cast time of Greater Heal and Prayer of Healing when Binding Heal or Flash Heal are cast.
    * We are also working to give Holy additional PvP utility.

Some of the reasons for the changes:

The Role of the Priest
The priest is a caster class that uses Holy and Shadow magic. Priests can only wear cloth armor and have a limited selection of weapons, but do most of their damage and healing from range. They make up for their low armor with spells that offer protection and healing.

    * Discipline -- this is a healing tree that emphasizes survival and single-target healing. Discipline specializes in damage absorption and prevention rather than restoring health, although they are very capable in that department too.
    * Holy -- this is a healing tree that has a spell suited for every situation. Holy priests can heal groups, heal individuals, heal tanks, or do all three in a single encounter. They are better at group healing than Discipline priests, but don't have as many damage prevention capabilities.
    * Shadow -- this tree sacrifices healing for damage. Shadow priests can restore health and mana to their group while casting their spells. Like the Shadow damage of warlocks, Shadow priest damage tends towards drains and damage over time spells.

Shadow Priest DPS and survavibility
We think Shadow priest damage is good in PvE and PvP, minus a few annoying bugs. We think the problem is that Shadow priests just can't survive long enough to do damage. That is a combination of some classes doing too much damage, but also Shadow defenses being too weak.

As a person with a Disc priest alt, I say w00t!

Hmmmmmmmm.... level Judi as Shadow or Disc. Hmmm....

• Abolish Disease: Now cleanses a disease every 3 sec, down from 5. Duration reduced from 20 seconds, down to 12 sec.
• Devouring Plague: This spell now has a new icon.
• Divine Spirit is now trainable at level 31.
• Holy Nova: Mana cost reduced approximately 20%.
• Hymn of Hope: This spell has been removed.
• Improved Holy Concentration removed.
• Prayer of Healing: This spell now heals the target's party, rather than being limited to just your direct party.
• Shadowfiend: Health scaling increased. Now receives 30% of the master's spell power. Mana return increased to 5%, up from 4%. The Shadowfiend now receives mana when its melee attacks land, rather than when it deals damage. Movement speed normalized to player movement speed. Tooltip revised.

Talents
Discipline

• Divine Aegis - Divine Aegis effects will now stack, however the amount absorbed cannot exceed 125*level (of the target).
• Grace: Duration increased to 15 seconds, but now is only limited to one target.
• Improved Power: Word Fortitude - Now also increases your total Stamina by 2/4%.
• New Talent: Soul Warding: Reduces the cooldown of your Power Word: Shield ability by 4 sec., and reduces the mana cost of your Power Word: Shield by 30%.
• Penance: Damage increased approximately 30%.This spell can now be cast on yourself.
• Power Infusion: This effect now has a new spell effect and sound.
• Reflective Shield:This talent has been removed.
• Unbreakable Will:Increased from 3/6/9/12/15% to 6/12/18/24/30%.

Holy

• Circle of Healing: Healing increased by approximately 40%.
• Holy Concentration re-designed: Mana regeneration is increased by 16/32/50% for 8 sec after you critically heal with Flash Heal, Greater Heal, Binding Heal or Renew.
• New Talent: Empowered Renew: Your Renew spell gains an additional 5/10/15% of your bonus healing effects, and your Renew will instantly heal the target for 5/10/15% of the total periodic effect.
• Serendipity re-designed: When you heal with Binding Heal or Flash Heal, the cast time of your next Greater Heal or Prayer of Healing spell is reduced by 6/12/20%. Stacks up to 3 times. Lasts 20 sec.
• Test of Faith: No longer increases critical effect chance of your heals, but healing done on targets lower than 50% health is increased from 2/4/6 to 4/8/12%.

Shadow

• Blackout: This talent has been removed.
• Darkness: This talent is now in tier-1, moved up from tier-6.
• Dispersion: Now clears all snare and movement impairing effects and makes you immune to them while dispersed.
• New Talent: Improved Devouring Plague (Shadow): Increases the periodic damage done by your Devouring Plague by 5/10/15%, and when you cast Devouring Plague you instantly deal damage equal to 5/10/15% of its total periodic effect.
• Shadowform: Bonus damage from critical strike chance removed and replaced by the ability of those periodic damage spells to generate critical strikes.
• Silence: Range increased to 30 yards.
• Vampiric Embrace duration increased to 5 minutes, up from 1 minute. PvP duration is now 60 seconds. Cooldown removed.

I'm not sure what I think about the removal of Hymn of Hope. I didn't run OOM a lot but I would occasionally use it if I saw other mana users running low.

I like that POH works on any group within a raid. I wasn't finding too much use for it raid wise since most within my group weren't taking the damage.

I definitely like the change to Shadowfiend.

No more reflective shield? That's a pretty big nerf to pvp.