I was fairly leery of this movie from the beginning as I understood it to be a vampire movie. I feel the entire concept of vampires has been watered down and bastardized to the point that they're more of a joke than a monster (see Twilight). However, I was pleased to find that Let the Right One In sticks very close to the original vampiric lore. While we don't see much in the way of gruesome transformations or giant bat forms, the general concept is maintained.
While it may have been the cultural difference, or perhaps the story itself, to me this film was
very melancholy and low energy overall. It's a fairly long story to chew through and even the more dramatic scenes (a woman bursting into flames, three boys being attacked and ripped apart, etc.,) will do little to raise your pulse. The most energetic part of the movie (also one of the few parts with much special effect work) is when a woman is attacked and thrown down a flight of stairs by a flock of cats.
In fact, in the way of 'horror' this film leaves much to be desired. The only 'monster' is a pale 12 year old girl with big blue eyes and an endearingly sharp wit. The only 'scary' characters in this movie are the normal human boys who antagonize the main character on a daily basis. Which, a credit to the writer, is a beautiful message in and of itself.
Overall this movie was melancholy and profound with layers upon layers of meaning and messages. It's a beautiful story with fair acting and wonderful character depth. But I found it to be more of a drama than a horror movie.
My final rating is: 6 out of 10. A beautiful, quality work of art. Just not a scary horror film.