Face it, books are not news. Not when there are 2,000 published every week. What you have to do is sniff out the news story, create a news story, or tie your release to a current news story. A press release is not a book review. It is also not a flyer or ad for your book.
Editors trash anything that even resembles an ad.
Often what I do is find the news angle and then plug the book within the story. Sometimes I quote the author, and mention the book as evidence of the author's credibility. I rarely focus the release on a book. Boring editors, rather than helping them. Most releases written by authors are long, wordy and boring.