Fran's voice is amazing. She sounds like Bjork, yes, but that in itself is a feat to be had by few. And I listen to Bjork, so I may be biased...
To be honest, I was expecting a deep, silken, sexy voice for Fran, but to hear one much lighter, heavy with this interesting accent, it pulled me in. It makes her sound like a different race, which she is, obviously. If she simply sounded like another hume, it wouldn't be much of a care.
And Baltheir's voice... My god, his voice is superb! Everything about him exudes elegance tied with a rough, blunt edge, and his voice simply adds to it. From the witty remarks to the kurt replies, it's wondrous.
Penelo doesn't sound annoying, ecstatic overs nothing, I'm on crack and thus I am somewhat annoying *cough Rikku cough*... She shares certain attributes, but her voice and character fit her well.
I could go on and on, but the fact of the matter remains that I believe this Final Fantasy to have the best voice acting yet.
My only complaint lies with Vaan since he sounds like he is plagued with a perpetual cold virus.
Oh, and what of this, uh, Mark-qweese and Mark-qwis? Is this pronounciation of marquis driving anyone else mad?