Axel's voice was one of the best. I hate Hayner and Olette's voices. Kairi's was much better in KH2. She sounded mature. Her KH1 voice was terrible. She sounded like a 10-year-old with a cold.
I think they are the only Nobodies that have hearts and emotions. They were the only Nobodies that didn't try to gain access to Kingdom Hearts. DiZ said himself that Roxas had a heart.
They were the only two Nobodies whose original selves didn't stay heartless.
They didn't fade back into darkness.