Made it to 80 on my Death Knight (finally) a few weeks ago. Ever since then I’ve been farming money from quests and dailies to get my epic flyer and the skill to fly in Northrend. I got that a few days and 6200g ago *cry*.
But it’s nice, I’ve done already some heroic instances and got some pretty sweet gear which has enabled me to kill almost anything I come across (even other DKs). So far the only thing that’s been able to beat me continually are mages, as they have the ability to kite me to no end. And I certainly don’t feel like re-specing to Unholy just to get leverage on one class, meanwhile lose my advantage on every other class.