Normally, these big nasty stat blocked characters/monsters that are supposed to be unbeatable like the Tarrasque aren't that scary to me.
But, that's primarily because those monsters are meant for the highest tiers of play where abilities of players begin with, "Once per day, when you die..." or are at a range where players have devolved into a *#$% measuring contest between players.
However,
's stat block scares the crap out of me as a perspective player and I'll tell you why:
TDF isn't about going from lowly Wizard in the Phonebook to the White Council's new age Merlin. TDF so far has been, new powers, new problems, same old crap, different day. No matter how much new stuff Harry gets to make life easier and himself more powerful, the more his normal problems weigh him down.
The stated outsider is not meant to be a big threat you will only be able to beat in epic tier, it's meant to be a threat you cannot beat, ever. As a player, if the GM pulls that character out in the storyline I wil be scared because I know me and my group cannot beat it.