Of course, there's always the issue of the book being better than the film. That is true here as well, even though I'm not a big fan of letter-writing novels, because they are always unrealistic; for the sake of exposition characters write each other with a frequency and level of detail (whole dialogues recollected to a word) that would never happen in real life. But the novel was a good read, lots of historical detail, lots of character depth, it felt like I actually got to know these people.
Which is why the film upon rewatching isn't any good anymore. Half of the characters from the novel have been removed and some of the others have been given a complete character change. Especially the character of Amelia, a feisty, strong, independent and warm woman in the novel, has been turned into a nagging, scared, vengeful, closed person. This is clearly done for suspense's sake; whereas in the novel the protagonist Juliet quickly learns all the details of what happened during the Occupation and the focus of the novel is her trying to write a book about it, the film has her worm out the details from everyone on the island, as if she is some sort of detective. The actual writing of the novel is shown in a quick montage of 'Juliet writes' shots. I realise watching someone write is not the most appealing image, which is why in the film most of the letters have been replaced by telephone calls, but her actually writing a book is somewhat essential to the plot. Apart from characters being dismissed or changed, the film focusses solely on Juliet's experiences, so we miss all the insights from the other characters, who in the novel are also writing letters and give an outsider's perspective to Juliet and the goings-on.
So did reading the novel ruin the film? No, but it put it in a different light. Knowing everything they left out, the film suddenly seems poorer in that respect, but stronger in elements that are not in the novel, such as the actual impact WWII had on British and Channel Island society. The message of the film is so different from that of the novel, that the two hardly compare. They are two takes on the same story, but the film should not be called an adaptation of the novel.
So they both have their merits and I enjoyed both. There is just one thing in the novel that really annoyed me (which luckily the film did do without): at two crucial decision making moments, Juliet's friend and publisher Sidney enlightens her on her own feelings and basically tells her what to do (in a letter). As if she cannot make up her own mind! For such an intelligent and wilful character, who fights her way out of the grasps of a controlling American suitor, having a man give her these insights just made the book that much poorer.
