@Heilig:

Well it actually is just as good as an on use ability for planned use to survive a particular boss ability. If as you say, healers let you drop and the 2 minute cooldown is in effect when you were going to need it for the boss ability that just means the healers caused the wipe, not your class. A warrior needing to use last stand would have simply died. Instead you lived long enough to die when you were planning on using the ability. What's the difference?

I'd go so far as to say it is vastly superior to last stand because it can be used to save the paladin from a single hit that would one shot a warrior even if they had last stand up. This ability will be only the second added to the game to provide this kind of ability, and the first time a tank has it inherently (rather than needing it to be cast on them by a healer). The only other ability that exists that can completely avert death is guardian spirit.

I for one am going to love this ability in PvP. Prot PvP healing is getting to be more and more attractive every day (massive damage reduction, 20 cooldown on stun, 30% larger crit heals, 30% of stamina converted to SP, unlimited mana regen on demand). I strongly recommend that blizzard rework the talent that converts stamina into SP.