I'm honestly most interested in the new Quests. I love them, and plan on doing the new Loremaster Achievements for them straight away, I'd like to see how they're implemented, not just in the new zones but the older changed ones as well.
I also once wrote the Shaman FAQ, but after my account got hacked and I switched sides I never went back, so looking forward to leveling a brand new Goblin Shaman and renewing that whole thing. Goblins are just awesome. Only after my Druid hits 85 though..
As a healer at heart, I am really, really excited (and scared) to find out how the new mana regen mechanics/stats etc change for the good & bad. You mean I actually have to use Innervate this fight?
ON MYSELF?!? ... .. Sh*t.