It won a slew of film festival awards, and I have to say they are deserved. A one-sentence summary of the story could leave you thinking that it is a generic genre film, but it is not. It is touching and evolves at a leisurely pace. The ending was happy, and charming, and only after looking at the IMDB summary did I fully understand it.
P.S. - The title apparently comes from a song by Morrisey, Let the Right One Slip In, which ends with the lyrics:
Let the right one in
Let the old things fade
Put the tricks and schemes (for good) away
Ah ... I will advise
Ah ... Until my mouth dries
Ah ... I will advise you to ...
Ah ... let the right one slip in
And when at last it does
I'd say you were within your rights to bite
The right one and say, "what kept you so long ?"
"What kept you so long ?"