Whether you are a film snob, or casual film fan, whether you know everything about film or nothing:
Both are decent films.
Both are close to the book in their own ways.
Both have value.
Ultimately, you will probably enjoy either, but will prefer whichever you saw first.
I saw the swedish version first, and so the american one felt unoriginal and unnecessary. There were aspects that were closer to the book (such as the inclusion of the main character's daughter), but generally, I think whichever you watch first you will enjoy, and the other will seem too similar...