just saw this today, and ditto with reporting on the blood DK, have been DK tanking since LK put in the LFD system...
so, i look forward to seeing how it handles plague tap, as i never really get the hang of PT :/ (not enough toolbar space)
afaict, pre-60, it's a weak tank, after 65, it picks up once you get rune strike and ibp, prior to that it's hard to keep threat with people using heirloom gear and there's lots of downtime where there's no filler ability to hit for resources.
the majorly different part of CR'ing (and playing) a DK tank is just handling threat, moving mobs with diseases (moving mobs to/with you & keeping up threat) and active's (shielding/stacking or pre-empting burst damage)
each of the 5 tanks all play very differently with active mitigation, the DK feels like a melee caster, juggling dps, threat and positioning, survival CD's and dps CD's and the "emergency" abilities that give you choices between dps and survival CD's. it's a lot more strategic than i expected.
mechanically, it's simple. tactically, it's not as proc-heavy as other specs, and you get a little bit of freedom to make mistakes.
should be fun to see how the CR goes.