So, I am not really a "vampire" kind of guy, I think, with the exception of the bizarre, hilarious Francis Ford Coppola Dracula, and if I'm being totally honest, I didn't really like the original Swedish Let the Right One In, which I found kind of emo and goth-y and boring. But tons of people really loved it, and I hate movies that involve "sentiment" and "emotions" and "nuanced characters" so... I am probably not the best judge. (On the other hand: I really loved Cloverfield, which I think puts me in the minority.)
The movie—based on a bestselling Swedish book—is a dark little fable about a kiddie vampire (or, well, a vampire that resembles an adolescent girl) who sets up shop in a small town and befriends a wussy tween boy. The original was somber and moody, and the footage in the trailer seems to match the gloomy tone, even if the action has moved from Sweden to New Mexico (in the high desert though, so there's snow). I can't say much more without giving away important plot points, but if some poor doomed marketing executive is hoping he has the new Twilight, he's in for a rude awakening.
Reeves has said all the right things about the remake—that he loves the original; that he refused to make the main characters older—which would to indicate that he "gets" it. Even so, I'm not sure why we needed a remake. I guess vampires are way hot right now, and someone is out there ready to make Let Me In-themed lunch-boxes or temporary tattoos or daily vitamins or something. Next time, let's do Kolchak.