Chrono made various very good post and reply on different about drk issue.

He goes in great details as to why and how much weaker DRK.

For me the most important weakness that I hope will be addressed are the lack of raid utility compared to WAR/Pal and the missing cd.
People talk a lot about that 5% missing dps (which is adresses anyway) but I honestly didn't really cared about 5% tank dps. My first job is to survive with the boss on my face, I'm more worried about missing survivability as a tank than missing a few % dps. I can't recall a single case where me doing 5% more would have mattered.
But I can recall many times where some sort of Aoe TBN would have saved the raid from a wipe