I like her, but I feel like her disapproval and approval is way too inconsistent, probably the worst out of any character.
If you don't like her you can always just kill her instead of taking her along.
I don't know if I'd describe Shadowheart's approval as inconsistent. She just doesn't easily fall into the "good deed vs bad deed" binary most people assume characters should fall into.
From my experience with her Shadowheart is a neutral good person who's trying to be neutral evil. Basically she's a fundamentally good person who is striving to be a self centered pragmatist who can do what is necessary to further her personal goals.
She likes it when you ignore people's pleas for help and dislikes it when you agree to go out of your way to help someone, but she likes it when you help people after already agreeing to do it. She dislikes it when you perform senseless acts of evil and dislikes it when you pick unnecessary fights.
Keeping that personality in mind I find I am rarely surprised by her reaction to things I do. It might seem counter-intuitive, but that is because it is. She's a bit hypocritical. Which comes from the fact that she's part of this religion that espouses virtues of selfishness and pragmatism that don't necessarily align with how she genuinely feels.
So she'll go along with attacking the grove because she rationalizes it as the pragmatic thing to do to further your goals. Then she'll get drunk as Hell because even though she's telling herself it had to be done she still feels guilty about the deed because deep down she knows it was wrong.
Honestly she's probably the most complex of the current followers.
It's just a shame she's mechanically so weak comparatively.
