I did two heroics with my DK yesterday. It was my first time to do heroics with him. Both went really well (same group). I got a chest upgrade, Breastplate of Undeath, which I still have to enchant. I was also doing a lot more DPS -- about 2k against bosses -- than the two casters (warlock and mage) who were in the party.
I'm hoping that the changes to Death Knight mechanics will not lower my DPS at all. It is nice to be able to do 2K with crappy blues. It just means that as I start to get better gear for him (Naxxramas purples, possibly?), his DPS will only improve. Good fun.
My Priest is level 73. I have made a small dent in Dragonblight and will continue questing there until at least the Wrathgate questline is done.
I hope to continue working towards at least heroic gear for Mordreth. Gearing up a melee toon as fun as a Death Knight makes the game enjoyable. :)
Gaiwyn of Proudmoore