I like this series. In the anime, Yukino changes her personality because of Arima. She doesn't stay the same.. forever anyway. She turns out to be a nice person who, as we know, wasn't the nicest of people because of what she did. That's what makes it interesting, I think.
There is no nudity at all in the anime, as far I know. I've watched the whole thing and there isn't any at all.