Respec gives you back every point you have spend. It won't affect permanent passive boni like the +1 Tenebrium quest reward or the +1 Intelligence / -1 Perception book.
Things worth noting about the respec guy is that you will have to buy / find the skillbooks again and that he also offers to give you 10 Ability points for unspent Talents and 1 Attribute point for 5 Ability points.
