Well, Witches are prepared casters, so there's that difference. Also, while I haven't yet studied the spell list too much, I can say that I'm not building a healer or scholar out of this one. I think there's going to be a dark streak to this character.
Yeah, there's a lot of debuffs and creepy spells in there; I think Mithril would love it. And meanwhile Soren is dancing and singing and doing buffs and illusions.