My fav song from her is Sakurairo Mau Koro, a very very good ballad IMO.
I rem when she first debuted, I didn't really like her at all, felt that she has this really 'cold' look. But subsequently after checking out her PVs and listening to her singles, I would say she's a really good jpop singer, mostly with jazzy ballads. Very unique singer I say, she's one of my favs now.