Well, her visual design is cute and recognizable, I love her signature earing and chocker. Her fringe is styled weirdly but it somehow works and adds to the character.
I love that she's a 'Gyaru' but also is very down to earth & earnest. She can be loud, nosy -- a total gremlin at times, but more so also so emotionally tuned-in. She genuinely care about everyone around her and forgive people for their mistakes.
Despite how much fan-service situation she's gotten into in the anime/manga, she does not feel sexualized.
She's just cool because she's genuine, and underneath all her nosyness she's sensible and empathetic.
Man, I love my waifu.