I've read quite a few replies already to help get some ideas flowing, and I kind of expanded on their ideas a little bit. I'm probably going to get trolled for saying this, but I think Blizzard did a very, very good job with priests, and I'm almost afraid to make suggestions because I enjoy playing it how it is right now... But I understand changes also are what keep the game interesting, and knowing how much Blizzard loves priests (compared to, oh, let's just say pve resto shamans), I'm looking forward to new methods/etc.
What type of content do you focus on? Both, but certainly more emphasis on Heroic Raids.
If PvE, what type of PvE? Heroic progression.
If PvP, what type of PvP? RBGs.
What are your biggest quality-of-life issues? HoH is very, very amazing. When I use it in conjunction with shadowfiend and a volcanic pot, my max mana gets to around 220k+, and my useable mana is about 180k+, which makes me giggle. However, Divine Hymn is lackluster when not used in conjunction with (glyphed) barrier, and is not up more than once a fight like barrier is, (save for Rag if you use it early, which is probably not a good idea anyway).
What makes playing your class more fun? I feel like I need to put everything I love about priest healing in here so nothing ends up getting taken out/nerfed/ignored. I essentially like everything about it, particularly how many useful CDs I have. Pre-bubbling the raid with a 58k DA stack makes me giggle. Also, my PW:S and DA take precedence over other healers' hots and direct heals, and PW:S functions as a 30k+ instant cast heal, and when used in conjunction with SoS/ToT, I feel like disc is the best tank healing spec out there currently. This patch seems to have a lot of predictable damage which, because my bubbles take precedence, makes it fun. I also feel like mind spike with a mind blast after (boulders for H Alys, transitions on Rag) is actually somewhat beneficial. If someone misses an assignment, I feel like I can pick up a portion of the dps on the add/boulder and actually do 50k or so damage to it in the 5-6 seconds that it needs to die. Lesser heal is also greatly undervalued (particularly by Holy priests since they could be doing something else), as it's a very mana-efficient way to SoS off your PW:S debuff. I also love the ability to lifegrip someone that's standing in fire, or otherwise being a baddie and not where they're supposed to be. (I *may* or *may not* also lifegrip people into lava when we take a break while raiding, too...) PVP-wise: Mass Dispel is phenomenal. Mind Control is absolutely amazing. Nothing makes me giggle more than when I MC that annoying rogue off the cliff at LM. There's no greater feeling knowing that I frustrated the other healer(s) after I power infusion/mana burn them to OOM too. Fear is perfect as well.
What makes playing your class less fun? Pre-bubbling the raid feels like it's mandatory since there's no reason to not do it (Alys/Domo for example). Because my bubbles take precedence, I feel like I have to always be watching aoe ability timers (seeds on Rag, stomps on Rhyo, et cetera). It's not "not fun", but it can get to be a little stressful (which isn't necessarily bad as a healer). As haste seems to be more throughput HPS than mastery, I do not feel as though I'm making much use of my mastery. A solution would be to make mastery scale up more and reduce the initial bubble of PW:S, but that wouldn't feel very balanced in my opinion. I honestly can't think of anything else that makes it not as fun as other classes aside from D Hymn having an excessively long cooldown, without some way to work the CD down (something similar to Train of Thought perhaps?)
How do you feel about your “rotation”? I predominantly play disc, and feel that the disc toolkit is very flexible and I have numerous options depending on what the incoming damage is going to be. Holy feels weak because their mastery is a HoT, which a majority of the time does not get the full benefit used. CoH is very fun to use, but PoH being based around raid groups makes some things complicated at times (if you don't set the raid frames up for pillars in 25man Nef, PoH becomes a HPS loss). Again, CoH is great for that, but it has a long CD compared to being able to PoH spam. But perhaps that keeps people from glyphing/spamming PoH like it's their job.
What’s on your wish list for your class? I really, really enjoy disc as it is. I'd like to see smite healing fall to the wayside though.
What spells do you use the least? Shackle undead (though, it makes sense for a "priest" to be able to only shackle something that's undead, unless it's an undead priest????), Holy Nova. I completely and totally despise AA/Atonement priests, as I feel it's a huge HPS loss.