Pope Leo XIII says about the importance of saying the rosary like this :
“Let all the children of Saint Dominic rise up for the fight and let them, like mighty warriors, be prepared to use in the battle the weapons with which their blessed Father, with so much foresight, armed them. This is what they have to do: Let them plant everywhere the rosary of the Blessed Virgin Mary; let them propagate and cultivate it with fervor; through their assiduous care may the nations be enrolled in these holy militias where the ensigns of the rosary shine; may the faithful learn to avail themselves of this weapon, to use it frequently; may they be instructed in the benefits, graces, and privileges of this devotion.”
Here are the 15 promises of the rosary:
1. To all those who shall pray my Rosary devoutly, I promise my special protection and great graces.
2. Those who shall persevere in the recitation of my Rosary will receive some special grace.
3. The Rosary will be a very powerful armor against hell; it will destroy vice, deliver from sin, and dispel heresy.
4. The rosary will make virtue and good works flourish and will obtain for souls the most abundant divine mercies.
5. It will draw the hearts of men from the love of the world and its vanities and will lift them to the desire of eternal things. Oh, that souls would sanctify themselves by this means.
6. Those who trust themselves to me through the Rosary will not perish. Whoever recites my Rosary devoutly reflecting on the mysteries, shall never be overwhelmed by misfortune. He will not experience the anger of God nor will he perish by an unprovided death.
7. The sinner will be converted; the just will persevere in grace and merit eternal life. Those truly devoted to my Rosary shall not die without the sacraments of the Church.
8. Those who are faithful to recite my Rosary shall have during their life and at their death, the light of God and the plenitude of His graces, and will share in the merits of the blessed.
9. I will deliver promptly from purgatory souls devoted to my Rosary.
10. True children of my Rosary will enjoy great glory in heaven.
11. What you shall ask through my Rosary you shall obtain.
12. To those who propagate my Rosary, I promise to aid in all their necessities.
13. I have obtained from my Son that all the members of the Rosary Confraternity shall have as their intercessors, in life and in death, the entire celestial court.
14. Those who recite my Rosary faithfully are my beloved children, the brothers and sisters of Jesus Christ.
15. Devotion to my Rosary is a special sign of predestination.