It’s essential to read the book review by Joseph Bottum:

Warren Zevon was a minor genius, ridden too hard by his demons to make the move to major genius of the pop-music genres in which he worked. His greatest achievement may be that he was himself and only himself, an artist who had only the smallest of gaps between the on-stage persona he constructed and the off-stage person he lived. In lyric after lyric, he produced songs that could only be by one writer. In performance after performance, he delivered work that could only be by one singer. In episode after episode, he lived a life that could only be by one person—the genius and the disaster that was Warren Zevon.