If you have read the book, the film is a shock as the story line has little resemblance. Although the stories start the same, the book and the film soon diverge. Gone are the clever twists and turns, gone is the mystery and bournes feeling of utter dispair as sinister events emerge around him. Gone is the core of the original story, the international terrorist Carlos the Jackal and the complex intrigue around him, the international conspiracies, the betrayals and gone is the crucial leading lady (replaced by a much weaker character). The eighties version, with Richard Chamberlain and Jaclyn Smith was much truer to the book.
Having said all that, this film is very good. You become sympathetic to Bourne (well played by Matt Damon) who struggles as the wounded amnesiac who discovers his mulitple identities, that everyone he meets either wants to arrest him or kill him and his ability to disarm and disable police, soldiers and assasins alike. He slowly works out who is behind his problems, his true identity and role in the dangerous world he finds himself in. His leading lady doesn't need to be the strong willed doctor of the book, because there is less for her to contend with in this simplified plot.
The car chase is good, the martial arts are good and the modified story, despite some obvious flaws is good enough.
This is worth watching if the proper tale of Bourne and his complex Identity doesn't bother you.