I've only just gotten Minthara into my party but there are definitely some bugs with her.
For instance, I rescued her from the dungeon before getting the moonlantern from Balthazar's room, and she kept initiating dialogue with my character every five seconds to tell him that she wouldn't follow him upstairs. (And this is after I tried to tell her to wait downstairs!)
The way her dialogue tree is constructed is also different from the rest of the companions, which strikes me as a rushed fix to get her commentary on everyone else. She does have some very incisive comments on the rest of the party, though!
It's really a shame to have to give up three companions to get a kind of broken one.
