The following is the opening paragraph of Pope John Paul’s letter on the Rosary http://www.vatican.va/holy_father/john_paul_ii/apost_letters/documents/hf_jp-ii_apl_20021016_rosarium-virginis-mariae_en.html
The Rosary of the Virgin Mary, which gradually took form in the second millennium under the guidance of the Spirit of God, is a prayer loved by countless Saints and encouraged by the Magisterium. Simple yet profound, it still remains, at the dawn of this third millennium, a prayer of great significance, destined to bring forth a harvest of holiness. It blends easily into the spiritual journey of the Christian life, which, after two thousand years, has lost none of the freshness of its beginnings and feels drawn by the Spirit of God to “set out into the deep” (duc in altum!) in order once more to proclaim, and even cry out, before the world that Jesus Christ is Lord and Saviour, “the way, and the truth and the life” (Jn 14:6), “the goal of human history and the point on which the desires of history and civilization turn”
The Rosary, though clearly Marian in character, is at heart a Christocentric prayer. In the sobriety of its elements, it has all the depth of the Gospel message in its entirety, of which it can be said to be a compendium. It is an echo of the prayerof Mary, her perennial Magnificat for the work of the redemptive Incarnation which began in her virginal womb. With the Rosary, the Christian people sits at the school of Mary and is led to contemplate the beauty on the face of Christ and to experience the depths of his love. Through the Rosary the faithful receive abundant grace, as though from the very hands of the Mother of the Redeemer.