I watched Let the Right One In
and Let Me In
back to back. I started with the Swedish release, expecting to like the American version better. The higher production values and non-foreign sensibilities usually win me over.
But I was way off. The thing is, the movie completely hangs on the girl's performance, and Hedebrant (Swedish) is significantly better than Moretz (American). They also chose a much better look for her in the Swedish film, using a combination of makeup and costume that definitely left the impression that there was something wrong with this girl.
As I think someone may have alluded to above, the uninvited entry scene is leagues better in the Swedish version. In fact, I kept wondering if they were going to actually do
anything with it in the American ("...any second now").
As for the pool scene, I have seen a few people (including reviewers) say that they felt the Americans really screwed up the finale, but I honestly did not see enough of a difference to matter or care about. In fact, aside from a couple of positional / direction changes, they are nearly identical. Enh.
If I could mix and match though, I'd take the American boy. The Swedish boy (character) seemed much like a low-functioning retard whereas the American one just seemed like an average kid.
Also, I'd take some of the refinements made in the American script. Three in particular stick out in my mind, involving her first protector (the nature of their relationship), the note she leaves for the boy (timing), and another subplot I won't mention here (for spoiler reasons) that was entirely excised in the American version probably because it served no point (that added... what to the story?).
Is it better enough for a second viewing? Enh, probably not. Its still nearly the exact same plot (scene-for-scene almost). But if you are going to watch it again anyway, go ahead and pick up the Swedish version. Grab the BluRay edition though. I understand the DVD has some truly horrific subtitling.