I'm still pondering why the film always held me at arms' length from its deeply emotional content. The characters tended to spell out their experience too much as they talked about it. The dialogue was a little too calculated for me. Explained emotion rather than raw, living emotion. The one scene that got at it for me was when Del Toro is coming down off a heroin fix and Lopez asks him several times what he needs, what she can do to help him. He tells her he wants "Chocolate" - and the next time she asks: "ice cream." These short exchanges communicate the longing, guilt, desperation and raw physical experience that draws a more striking response from the viewer.