1.) It's hard to compare yourself to other healers. I mean, I healed 2.5M and did 2.5M DPS in Warsong Gulch. Died several times and ran right back into our flag room to heal. When you see that the enemy Druid in the room did 16M healing and 2.5M DPS, it's a bit disheartening. Then you see your Druid is 10M healing. The Paladins are up there too. Their mana bars always seem full while I go OOM despite throwing out a Mindbender every time it's up. You just have to detach yourself from that.
2.) I feel like our style is a bit disconnected. We want mastery to increase our absorbs, but my crit is much lower than it's ever been. So I'm not getting enough Divine Aegis procs to really justify having a high Mastery. When you have 3 stacks of Grace up, hit Archangel, Inner Focus and pop a greater heal onto someone, it's sad to see it really only hit for 150K when you know that Shaman just used less Mana on a Greater Healing Wave and did 250K. (Arg, I need to stop comparing myself to other classes. Or just hope that my aegis makes up the difference.)
So it's really a crazy thing... I need to keep Grace Stacked up on my targets. But now with Atonement, if you're casting Penance on someone in a melee type fight who already has Grace on them, you're wasting the healing. You should be throwing out DPS. It doesn't seem to hit that hard nor heal that much. But you're going to need Archangel again, so you have to get Holy Fire and Penance out there to build it up again. The skill cap is really upped for Disc... you have to know when you restack grace versus DPS Atonement versus straight up cast healing.
3.) Void Shift as a 6 Minute Cool down is cruel for PvP. First off, you can't really use it when someone is low. Yeah, there's a 20% increase to the lower party, but if they're being trained or you're being trained, a few hits with the burst dps around can kill you. So you have to use it when someone is nearing the 30% mark, so you have a little more breathing room. It's not really an emergency button at PvP, it's a "well, I might as well use it" type of ability. I'd really love to see a lowered cool down on PvP gear, like on the wrist or part of a Set Bonus. For PvE this ability deserves its 6 minute cool down. (Aside: I still need to test Holy on this - I want to know if the 20% is bumped up if you cast guardian spirit on yourself and then void shift someone who's low.) This wasn't the worst ability in the arena, but again, I used it when my DPS was at 20%, and my 40% HP bar was heroically leaped upon and eaten before I could do anything.
4.) Survivability is extremely low. With the talent selections, I felt taking the speed boot enchant was better than taking Angelic Feathers (and I'm really good with the feathers) or Body and Soul. Being able to Fade when the Poly is coming, or when faced with a lot of ranged trying to take you down or use ranged CC... it's the new Shadow Word: Death skill. Sadly it comes with a much longer cool down.
All in all, every class seems to be doing pretty decently against me. I think I did okay against some Hunters and Holy Paladins, but everything else seems to be able to take me down faster than I can take them down.
5.) Mind Sear as an AoE is sad. I'm glad they added the fact that Shadow Word: Pain can interrupt flag caps. I think that's a nice change. Any shadow spell seems really hard on my mana, so I try to avoid them as much as possible. This is leading me to more frequent spell lock outs. Since I try to keep Fear, Mind Bender, and Psyfiend on cool down, having access to Shadow Spells is well, not that useful unless one of those abilities are up. But if I'm being trained, then well, it's not going to matter much.
6.) It's not that the CC is out of control. It feel that way. It just feels that I used Psyfiend, Psychic Terror, and both the DK and Warrior always have the "immune" message light up. I try to time it so it's not AMS'd or Berzerker Rage'd, but I seem to die faster than I can wait it out. It seems my best hope is Spectral Guise, move away, Inner Focus a Greater Heal, Fade, and fear / run. But it's all so tenuous at best. I try to use Line of Sight as best as possible, but not all BGs and Arenas have that. And well, sometimes people die because you LOS'd them.
7.) Dispels. I get that we need to dispel a whole lot more mindfully now. But I think Priests need to dispel two buffs offensively as a baseline. Or I'd take an 8 second cool down on Dispel Magic if I could dispel all the magic buffs on an enemy. The big problem is that multiple healers in a pack (i.e. Druid and Shaman) can keep themselves up indefinitely. There's so many buffs to dispel on them to reduce their healing output that I go oom rather quickly. It's hard to DPS harder than they can heal. I try to do my part in that respect, but offensive dispelling against healers feels pointless.
8.) Glyphs. Yeah, yeah, yeah. I think every Disc Priest is lamenting the new glyph set up. I've been running with Penance and Holy Fire. I just feel like I need the movement the Penance Glyph offers, and an instant Holy Fire gets me to Archangel faster. I've ditched Desperation, because every three minutes is just too long to use a glyph for. I've rotated several through. My Inner Focus is still being stunned or I'm getting locked out (since Counterspell may not interrupt the spell but the lockout doesn't seem to be tied to it successfully landing the counterspell).
Renew is probably a better choice overall. It's far more mana efficient than the other choices. With us not throwing bubbles around, it's rough.
9.) Secondary stats. I can't wait for better gear because I'm desperate for the scaling. Power Word Shield is costly. Not having Borrowed Time that often means my Flash Heal is interrupted far more than I like. 4% Haste... Wahoo. Less DA Procs... wahoo. My feeling is like, "Well if I'm a lame Healer, well at least I'll be a lame dps too! That way I can feel twice as bad!"
10.) New Abilities. Halo was awesome for Arena to knock out the Mage and Hunter from Stealth. Costly, but nice. I rarely touched it because of the mana cost. I liked Divine Insight for PvP, because, well, in Arena it was nice to be able to bubble someone fast after their last shield was blown apart. But it may still be lackluster compared to Power Infusion. I think Power Infusion can be dispelled or spell stolen, so that may make it a liability than an asset. I have to check that out.
All in all, I feel like I have a lot to learn. But right now, the only thing I really felt was OP was having Cyclone in the Arena. OMG, that's just amazing to have a CC other than fear. Now if we could get a more reliable mana regen that a fiend that can be CC'd (and if your Dispel is down, cry at your lack of mana return!), we'd feel like kings and queens even if we still feel underpowered at PvP.