I made a short clip to show what the damage is like:
I realized we no longer have the passive talent "Focused Will" (http://www.wowwiki.com/Focused_Will). This talent was improved in Cataclysm to help with Discipline Priest's survivability. I'm not sure if it was forgotten or just straight removed for no reason, but priests definitely need more survivability.
You might say this will improve at lvl 90, but really if you look at our cool downs, they are no where near as good as other healers. A shaman for example has Nature's Swiftness, Spirit Link Totem, and Healing Tide, which are some of the most powerful abilities in the game.
All of our major healing cool downs have been removed. Divine Hymn removed for Disc priests, and Desperate prayer is most likely to be replaced by Spectral Guise by most priests.
What priests need right now is Focused Will again and more healing cool downs. Perhaps Desperate Prayer can be baseline. The removal of Divine Hymn for disc priests is also one of the biggest upsets in the history priests.
Another thing to mention is our mana. Our Rapture ability is really badly designed. Even if we stack 10,000 spirit, it still won't give back enough mana to outweigh the cost of a shield.
Please do some class balance...