eminem is definately overlooked because he is a rapper.
His lyrics are often very intelligent. even when full of swearing, etc, it is still very cleverly put together, and it takes a lot of effort to remember all the lyrics to perform it on stage.

If you forget the music, it is indeed clever stuff.

Like Foot said, broaden her musical knowledge. Play stuff by the experts. Play stuff from Pink Floyd and Led Zeppelin, to Christy Moore and Emmylou Harris, up to modern day with Thea Gilmore etc.