It is needless to say that the book is much better. It's a real classic spy story. But the movie adaptation was quite a surprise. It obeys the storyline of the book, but: (1) the first part of the novel is totally left out; and (2) the last 15 minutes are in many ways somewhat different from the novel. Nevertheless, these changes are quite understandable: they make the movie more agile, more suitable for the screen.
The main characters are very faithful to the novel. British actors are very good, well casted and well characterized. German actors are somewhat stereotyped, but go along. Fighting scenes, more often than in the book, could have been better performed. Scenery is beautiful.
For a 1979 movie, I should say it deserves a seven. Had it been filmed in the 21st Century, I think it could have another 20 to 30 minutes – so as to better explore the feelings of the main characters (as the book does in its first part).
