They took the best parts of the book and decided to get rid of them. They wrote their own drab story, and should of stayed true to the original content.
You don't feel for any of the characters as a result. There's no love story, then revenge, no bulld up of any of the characters.
It makes me scared for thr rainbow 6 movie. Are they going to use the absolutely incredible plot in the book? Nah prolly not. They gonna write their own cut and paste action movie, the only thing clancy about this is the character names.