I'm ~80 pages in, and it is different. The translation feels off similarly, but how the characters are presented is different. For now it seems the book has two heroes, two point-of-view characters. One is Rambo ofc, the other is Teasle, the sheriff of the town. They both have their inner struggles, both of their backgrounds are presented, their insecurities, their thought processes. Rambo is no way of a superhuman-fighter-machine. Making mistakes left and right, unconscious reactions they can't come over by sheer will or cool head. I think this isn't really comes off from the screen when watching the movie, but I have to rewatch to tell exactly. The motivations of Teasle can be seen and understood, even tho maybe won't wake sympathy towards him.
I reserve the right for final judgement, after I read it in whole.