I played Seelah in RotR and never regretted it! She was definitely my favorite character of the group.
The new Seelah is definitely looking strong - esp some of the tricks with the role cards.
i.e. Inheritor's blade with an armor that 'reveals' to reduce damage = "Oh look, the villain does damage to EVERYONE? Reveal..reveal..reveal..reveal. There we go all taken care of."
or for Wardstone Sentry - the d8 against any Demon/Undead (by the time you have a role, most of her weapons should be magic anyway), or the Charisma +2/4 for any before you act check.
This is almost making me want to play Seelah again, even though I had my eyes on some of the new characters. Guess I'll have to wait until I get to see everyone :D