I would not consider the author to be a "spiritual writer" simply because she published a book on her own, self-termed, spiritual journey.
To me, the book was more of the personal and journalistic approach that one woman took in an attempt to work out her relational, emotional, and in many ways, mid-life crisis type problems. I found her "spiritual" revelations to be lighthearted, and yes, personal, but somewhat trite and certainly trendy. In many ways, this book speaks to the modern and professional woman's plight to find happiness (fulfilment) in light of the fact that the struggle to gain equality (financially, success-fully, or otherwise) for many of such women, has been realized.
I'd label this book a feminist guide before I'd label it a spiritual guide.