Unholy has a lot to keep track of. That doesn’t really mean it’s complicated. Mastering it is a whole different ballpark.
There is a difference between a good Unholy DK and a great Unholy DK.
But the fundamentals of Unholy is not hard. You use Festering Strike to apply Festering Wounds. You use Scourge Strike to pop it. You keep track of Festering Wound for each mob (Kinda like a Rogue CP or Monk Chi on EACH mob with only ONE Finishing Move). You summon your pets. You manage your cooldowns of them and yourself. So on and so fourth.
I have not played WW monk for a very long time to make comparisons but Dks do have a lot of toolkits to synergize with each other. I believe you have what it takes to figure out the big picture that is Unholy as a spec as a whole. 
EDIT: Forgot about Virulent Plague DoT (From Outbreak). That’s important too!