I liked the Bourne movies, so when I found out that they are based on some books I decided to read them. Usually the books have more details that are not present in a movie, but in this case I was really surprised: the action from the books barely resemble what happens in the movies. Apart from the names of the main characters and the basic plot (a secret agent suffers from amnesia and fights for his life and to find out who he is) the rest is totally different. Although it dates from the cold war era and the technology described in the novels is now obsolete, the story of all three novels is far more entertaining and the conflict between various characters is doubled by the geo-political conflicts of that era, from U.S. and Vietnam to the British Hong Kong and the Soviet Union.
Of course when reading a book you use your imagination to picture yourself the scenes described there, but a movie always adds a soundtrack, so I will finish this post with the cool theme song of the Bourne movies: