It's skill list is roughly as good as a rogue, includes the all important 'use magical device, and the Corsair has better hit points and better saves.
It's a full progression spellcaster (9th level spells). While its spell list is somewhat limited, at low levels its got the ability to cast cantrips at will and at high levels it's got both Time Stop and Storm of Vengeance, which is nothing to sneeze at.
It's gaining roughly one feat equivalent ability per level on top of its spell progression. Most of these abilities are on the weaker side, and no one single one seems broken to me, but the whole seems pretty strong. You get the movement abilities and strong built in defenses of a rogue (slippery mind, uncanny dodge, freedom of action), decent attack capability, and pretty good spellcasting ability.
I don't see anything busted, and its probably weaker than a min-maxed full progression spellcaster at higher levels, but its also nothing I'd be in a hurry to approve either.
I agree with AS that this class doesn't strike me as flexible enough to be a base class. It captures a single exotic profession with a fixed non-customizable power progression. That screams 'PrC' to me.