I really wish I had said that.The film is a masterpiece of modern horror and manages not to be everything it is. Although this sounds extremely illogical, Let The Right One In is a horror film without a great deal of horror, a coming-of-age movie in which the protagonists don't really come of age and a romance in which there isn't a great deal of romance.
This is probably very close to the heart of the genius of this film: while it doesn't show a lot of of horror, coming-of-age, or romance on the screen, it still manages to generate a lot of each one in our imaginations. Tomas described this as engaging the audience in a dialog by forcing them to imagine the things not shown. For the most part, Tomas had us create our own horror, had us make Oskar & Eli come of age, had us make them fall in love, in our own imaginations rather than in his film. The most horrific scene was the pool scene, which we watched but was never really shown on the screen. We are shown Oskar finally grabbing the reigns of his own life by leaving with Eli on the train, but it's just a train ride. What it really means for Oskar's life is left to our imaginations. And as for romance, the closest thing resembling an open expression of love is the bloody kiss, and the smile that they share at the pool (and only one half of that shared smile is shown to us - okay, maybe 3/4). But that kiss and those smiles speak volumes in our imaginations.
I think that reviewer was definitely on to something.