Walid Shoebat was a member of the PLO, who has since renounced Islam. This makes him an apostate, one who has renounced Islam. It is punishable by death.
Any time an apostate writes a book about leaving Islam, we should be paying close attention...because they're risking their life by doing so.
Shoebat's books provide an insight into threat doctrine and ways to defeat the threat.
Check out his homepage:
http://www.shoebat.com/index.php