This game is totally interesting right now.  I wanted to play the Death Knight to get a feel for it and see which I would prefer.  I definitely think it would be awesome to switch over.  They are definitely very powerful chars at just level 55.  Here are the quests that I completed.  I am not going to give too much detail because it's likely something will change when it is released.

In Service of the Lich King - Redeem through portal at 48, 31 (walks around) Instructor Razuvious

[The Emblazoned Runeblade] 47, 31

[Dominion Over Acherus] 2nd floor (not using the portal) 47, 26

[Company of the Damned] 50, 32

[The Eye Of Acherus]
Back to Lich King through the portal on the 1st floor
48, 30

[Death Comes From On High] no coords.

[The Might Of The Scourge]
51, 34 through center portal

[The Scarlet Harvest]
52, 33

[If Chaos Drives, Let Suffering Hold The Reins]
All quests are in the area.

Also, here are some pictures.

Movies:
Getting my Death Knight mount
Getting my Ghoul on