Seen both movies but never read the book. A bit of page-turner, a dash of political discussion, this tale is told from the points of view of several of the people involved - hijackers, detainees, cops, transit personnel and various others. The author does a good job of differentiating these, and the atmosphere of early 70s New York also shines through in the attitudes of all involved.
Would the gimmick have been a surprise without the movies? Not sure. As another review pointed out, there are better thrillers out there. Worthy of four stars and a fairly quick read.