I'm not lvl 80 but here is what idon't like .

Note that i'm a new player so i don't know how it was back then.

so:
-Living dead is very clearly the worst invulnerability.It's only "good" if you have a WHM who knows what it does and it force that said WHM to use his best heal just for you when every other tank can just get away with normal healing.Benediction is supposed to be their "oh crap" button, not their "just for the drk" button.

-I wouldn't mind doing a bit less damage if the "rotation" wasn't so awkward.From what i'm getting, as a DRK you need to use whatever is available at the right moment.However, having the two skills using the blood gauge on the GCD is so AWKWARD to use.These two already need a condition to be used, why not just have them off cooldown ?
Or, if it stays on GCD, delirium should give a lot more mana than this.

-From what i've seen you can't know what attack is magical and what isn't.It's not just a drk issue obviously but more important for him because he has specific anti magic defensive cooldown.

Those are just suggestion, but at least , at the very least we need something done about living dead.It doesn't make any sense and is just raging for the healers if they're not WHM.