I think we need more claryfication...
Will it be a magic debuff? Can it be dispelled? <- My guess is yes.
It won't break repentance... nice! But what about other incapacitates/CCs? sheep, gouge, sap, blind, etc. If it does break everything but repentance, this dot will screw us up in arenas. Let's say you're in a 2v2 match, and you DS the healer just as his DPS runs to help him and your mage sheeps him just after... You'll pretty much, without a choice (other than NOT use DS) make him uncc-eable. It's pretty unlikely that the DS dot will be the only dot in the game to not break incapacitates and I think that'll really affect us.
Now, don't get me wrong... That dot has lots of potential! like, imagine if it wasn't a magic debuff, but rather physical and thus un-cloak of skill-able, we'd have an efficient way of preventing rogues from vanishing/going stealth, but knowing blizzard, it will be dispellable (just like any other pally spell with the exception of auras, big surprise there).
I really hope this dot doesn't mess up CCs. It can also be a potential problem in 5 mans and PVE. =/