I think she is a bit lame, she has an empty back story: a cop that becomes a goddess for no reason. It is impossible to know what she is feeling at times. Is she sad? mad?happy?
She has no sex appeal. It is like the designer wanted to draw a male then changed his mind at the last second. It is really possible to draw a manly woman heroine: look at Korra in the last airbender, or Kuvira in the same show. Honestly Fang should have been a better lead character than lightning.
To make a comparison: Lightning and Vaan in FFXII are lame main character, whereas Fang and Bash/Balthier were underrated side characters.
I think the creators of Lightning wanted to have kind of an average hero any player would identify to: boys and girls, middle aged men and woman ( as she is a mature character that raise her little sister and is a justice servant)... But consequently she loses any charism, she doesn't evolve in her emotions , personality or even physical abilities.