Blood fear, an instant fear that lasts 8, 4 and 2 secs respectively with diminishing returns, with such a short cooldown, literally allows you to take control of just about any fight against most classes without immunity to fear. Consider it as having 3 extra CC spells, on top of maybe Shadowfury/Mortal Coil, Succubus Whiplash or Felhunter spell lock, and Rain of Fire stun for destruction warlocks.
Burning Rush doesn't free you from snares, but allows you to get away at 4% HP per sec.
Unbound Will seems good and removes all DoTs or magical effects on you, while removing all CCs instantly, but at a min CD.
If we want to take Unbound Will over Blood Fear, it needs something more for its 1 min CD. Perhaps a temporary 5 second immunity to magical effects or CCs. Reducing its CD would be too overpowered though.
And if we want to take Burning Rush, at least give it the ability to remove remove all snares and give it a limited duration and a short CD, say 8 seconds?