Fortunately, between the new LFG system, changes to questing, and the newly available gear, I found I was able to get my priest ready to heal Icecrown Citadel in just 2 weeks!
Leveling through the new LFG systemI leveled with a Shadow spec (for soloing) and a Disc off spec to heal some dungeons, and my initial thoughts on the new LFG system were very positive. From 70-80 I ran each dungeon once, with VH 2-3 times. During this time I was only in 1 pug that didn't finish the instance and probably only had a total of about 4 wipes.
I also found that the new quest/map system was really amazing in zones that I didn't know very well, such as Sholozar Basin. It replaced the need for extra mods like TourGuide or Carbonite.
Overall, leveling from 70 to 80 took about a week.
Gearing up a fresh 80Once I hit 80, I decided to concentrate completely on Disc (I queued as both but, unsurprisingly, have never been selected for dps). After 3 days and about 40 heroics later, I had amassed full iLvl 200 gear with a few 245 pieces from triumphs: the Talisman of Resurgence and the Band of the Invoker.
Hitting the new 3.3 contentOnce I had at least 200s in every slot, I felt comfortable running the regular version of the Icecrown 5-mans.
After running them all once, I'd picked up a few pieces of 219 gear. Since I still didn't feel completely ready to dive into the heroic versions, I just kept queuing for these 3 and continuing to pick up the free 219s, and noticed that after another day or two of this I was finding it hard to OOM. The only way I could do it was spamming Holy Nova even on packs of 1-2 mobs. When healing regularly, I never even had to drink between my Hymn of Hope and Shadowfiend cooldowns, so I decided it was finally time to start into the heroic versions. Besides 1 failed PoS run, I've found them to be pretty smooth.