Friends are great, aren't they? Even if you're friend is a vampire, that's still pretty good. And if you have to stay with that friend until you die of old age, that just means you were meant to be together forever. And if you need to spend that time murdering people so your friend can drink their blood, I guess you... I think maybe you should get a new friend.
It's possible that kids watching Let the Right One In only see how cool it would be to have a vampire killing all your enemies, but I don't think that's very likely. Kids are generally smart enough to understand how horrifying the ending of this movie is. If they know what's good for them, they'll be too scarred to ever become friends with anyone ever again.
