Character design: I like how her design gives that "ojou-sama" impression, and yet doesn't fit into the 'blonde princess in white' nor in the 'goth evil princess' stereotypes, more like a merge of both. She's the most beautiful female character in the game, IMO. Also, her dress manages to be just as tight and reaveling as her snake theme, all with her elements and such, calls for. The only weird thing in her design is, ironically, that snake head popping out of the hair... thingy.
Combat usefulness: She was a good support character, from what I can remember.
Tilt factor: She is utterly necessary to the whole Dario/Karsh plot and also utterly necessary for the Lynx-poisons-Kid in Viper Manor's terrace event, therefore necessary to the God Save The Kid (terrible pun, I know) plot. Besides that, she plays her role as daughter of El Nido's ruler flawlessly, with a personality that, just as her design, doesn't fall into typical little princess stereotypes.
I'm giving her an A.