The issue of book vs. film is, for me, not that straightforward. If it is a question of craftsmanship, I think there can be no doubt the film is far superior. For me at least, the leads' acting, the film's visual beauty and Soderqvist's work leave me no doubt. One could dissect the novel to find to find a myriad of parts one could object to on technical grounds. But as I've said before, craftsmanship is not all. If it were, Ruben Dario's poetry would be among the finest literature ever written, but I personally have little interest in reading nonsense about a duke called Job and a dog called Bob. Of course you can wreck a good idea by bad craftsmanship, there are reams of writing with that problem. But these are just the very extremes.
Ultimately I prefer the book over the film, even though as I've said the film seems clearly better-crafted, and even though some of the plot changes seem to me improvements (no undead Hakan, less on sidestories, Eli trying the candy). But as characters, I like book Oskar and Eli better than the film versions (I'm not criticising the acting, I'm criticising the characters), partly precisely because they're less likeable. The book's more aggressive, more playful, ultimately kinder (when it comes to actions) Eli seems more human, and therefore less remote, than the film's more mysterious, sombre Eli. The book's more deeply troubled, more uncharismatic, more violent but also kinder Oskar I also like better. Also, the horror in the book (minus undead Hakan), for me, as I've said before, is what keeps the love story honest - the contrast is a big part of what makes both the horror and the love powerful, and the horror is strongly toned down in the film. There are also a few scenes I miss from the book, and of course the film has defects of its own. Maybe I'm more inclined to literature than to cinema anyway, a number of things I like in the book would not have translated well to the screen (like the kiss under the balcony), and a novel is generally a better medium for character development than a film, but these reasons for me tip the balance in favour of the book.
Perhaps I should explain more about my tastes: For me to like a work of art, with some exceptions I have to feel it expresses something about the human condition. If it's too otherworldly (this includes character that are too perfect), it doesn't work for me - which is probably part of the reason why I don't usually like horror, but I far prefer Berenice to Lovecraft; for me for example The Masque of the Red Death would be much better if the mysterious reveller were a simply a diseased courtier wearing no mask. My favourite genre overall is psychological realism (Dostoyevski and some of his countrymen, Stendhal, Camilo Jose Cela), even when there are clearly fantastic or at least ambiguous elements (Cortazar, Juan Rulfo and some other 'magical realism' writers). If the characters are too unworldly, or I just can't really empathise with them, then I can't care about them and the book is lost on me. Actually, one thing I'm not that happy with is Eli's Rubik's cube-solving abilities, in both book and film. Eli being a very intelligent child is good, but a genius in the strict sense is somewhat too remote. I prefer to imagine Eli has solved very similar, simpler puzzles before, with plenty of help or after a very long time and a lot of effort, and thus is a very intelligent child applying things she has learned over time, rather than a Ramanujan.
I have no moral objections to either book or film, though I would not give the book to a child. I very nearly tossed the book away and gave up reading at the library scene, but that was because I found what was happening revolting rather than because I found the novel morally objectionable. I don't think these scenes are distracting, even though they have no direct bearing on the main story; they are an important part of the horror.
Bli mig lite.