There is a strong debate out there today about what is fiction and what is non-fiction.
Authors have different viewpoints on this matter: James Frey, author of the controversial "memoir" A Million Little Pieces, says that a book only has to be semi-truthful to be considered non-fiction, Seth Greenland, a primarily fiction author, says that if even an ounce of fiction is in a book, it can no longer be considered 'non-fiction', and David Shields, author of Reality Hunger: A Manifesto, says that the whole debate is silly and the classification doesn't matter so long as the story is good.
I could go on to give my opinion, but, really, the only opinion that matters is the opinion of the author's. If an author wants to present a semi-fictitious story as non-fiction, that's fine. If an author wants to adhere strictly to the definition of fiction/non-fiction, that's fine too. The author is the one who writes the book, so they get to decide how they present it.
