See for yourself - recount after finishing Nexus:

1st is me
2nd is DK with Blood 2Hand
3rd is Elemental Shaman in decent badgegear
For now it seems that Frost and Unholy are farewell balanced out, a bit to much burst possible with Unholy at the moment, and I think Blood-Caked Blade needs some working... proccing way to less, maybe just every few mobs.
Blood is surely underpowered at the moment, there is no way to keep up with Frost or Unholy at the moment - and also I was thinking about my Trybrid specc, which may be usable in Raids at lvl 80, but for questing / leveling it's better to go Frost or Unholy at the moment. You lack the selfhealing, but you bash the mobs fast.
And for the critics out there... there are other classes who also do 7000 or 8000 crits, so we are not the only ones. And it seems to me, that balancing is focused on lvl 80 raids and not the questing before.