Nayuki: Didn't hear enough of her, but I'm kinda not liking it...
Yuiichi: Hard to get used to, but pretty decent
Ayu: Not the same magic as before, but I think they did a good job trying to make her understandable to a generic English audience. Remember, not everyone is a fansub viewer ^_^
Uguu: Translated the best they could to English, imo. Same reason as above.