The Bourne Identity movie is totally different from the book. The book by Robert Ludlum is a good spy book.
The movie just took the character names and some events but the rest is a whole different story. First, Jason Bourne is not a real assassin as portrayed by the Movie. I wouldnt call it a modern adaptation coz the plot is really different.
I watched the Bourne supremacy (Part 2) and it kinda followed the 1st movie - meaning : its probably not related to the book. I scanned the first few pages of the Bourne Supremacy book and confirmed that the 2nd movie is not related to the book.
I have no issue with the movie. Its really good. Action packed and keeps you on the edge of your seat. i heard there will be one more Bourne movie next year.
Theres a Bourne Identity mini series which was released 1988. The 4 hour show portrayed the book very closely.
Hope I could start the Bourne Supremacy really soon.