The apparition and resultant image (tilma) of the pregnant Virgin—which latter has remained intact to this day, and thus far, far longer than its materials would naturally warrant—were the most powerful of instruments in the conversion of the Aztecs to Catholicism. Indeed I should say that the spirituality of which the tilma was the focus grew as much in spite of as because of the rapacious, often brutal Spanish conquest and colonization. Nor do I think it accidental that the site, near what is now Mexico City, is close to the geographic center of the Western hemispheric land mass. I believe the whole phenomenon was God's instrument for spreading the true Faith to the Americas as the Protestant Reformation was getting underway in Europe. It is of enormous historical importance if nothing else.
Of course it has drawn its share of critics and scoffers, like all similar phenomena, such as the Shroud of Turin. But in convergence not only with other Church-endorsed Marian phenomena but also with the history of the Mexican people themselves, the authenticity of Our Lady of Guadalupe seems overwhelming. North-American Catholics should take more note.