Why did I buy the book?

Rating: 5/10 (9 January 2008)

OK, it was a good action movie. Did the director/producer decide not to use the book at all? Jason is supposed to be 20 years older than in Bourne Supremacy. The assassin "The Jackal", who missed Bourne in Paris 20 years earlier is gunning for the final showdown. The entire pretext of the book is that Jason is out of practice from going underground (retiring)for 20 years and relies on his trained instincts to survive one attempt after another from the Jackal prior to the conclusion.
I guess the fourth installment of Jason Bourne will follow the book, maybe titled "Bourne Ultimatum 2, the Final Showdown".
I give the movie a 5 just because it was a good action movie but if the writers are going to name it after the book, follow the book a little more than just using the correct name of Jason Bourne.