She was immature but that's good writing given she's a child and is supposed to be like that realistically. She's a decent comic relief character that doesn't interfere with dramatic moments like Mr. Satan does in the cell games and Buu arc, or most of the comic relief characters in anime in general. She's not deep or thought provoking, she's an ordinary girl, her character isn't pretentious like a lot of anime characters which saves her from being utter shit. Yeah she's boring, but she's hardly ever relevant anyway until the very end.
