I got to know about her from the TV anime series, ARIA. She has cute voice and sings well, but I feel that her singing isn't quite at the level of some of the best singers out there. It's kind of like being able to play a really hard piano piece, but barely and without much margin. She's still young and continuing to study music, so I'm sure she'll continue to improve.
As for the songs, they're composed by a number of impressive composers, including Kan'no Youko.
If you like her songs from ARIA, you'll most likely like this CD.