Much of the coolness factor was lost in this translation from the original Let The Right One In. They rightly focused more attention on the Overall Story Throughline (something American audiences need), but in doing so made what was once creepy and darkly psychological more...obvious. The strange hiccup that occurs when their relationship first begins ("I can't be your friend") can be attributed to the fallout of this approach.
In addition, the Main Character is more clearly presented as a Holistic Problem Solver with his focus on maintaining the tender balance between he and his fanged friend. In the original, this was left more open to interpretation--again, less obvious--and resulted in a film that was somewhat more approachable by Male audience members. Guys have trouble relating to characters who solve things holistically and thus can explain why, for 50% of the population, this film is a bit distancing.