I read the book and didn't know it was a memoir until a few weeks after I read it (in fact, I had no idea it was an Oprah book). I thought it was fiction. That said, I enjoyed the book. I like how he used language to tell a story.
Now that I know its supposed to "non-fiction", I can't believe that many people really believed his story.
I didn't give it alot of thought, but I just assumed it was a fictionalized account of his rehab. The whole style was sort of impressionistic and emotional. His relationship with Leonard was like something out of a crackhead Horatio Alger story, for example.
I guess I wasn't reading for historical accuracy and couldn't care less how much of it was imbellished or invented.
The marketing of the book, and the author's interviews, were dishonest, but the book itself was very well done. And nobody's getting their money back.