Isn't the Rosary repetitive prayer? Didn't Christ speak against it.

Matthew 6:6-8

But when you pray, go to your inner room, close the door, and pray to your Father in secret. And your Father who sees in secret will repay you. In praying, do not babble like the pagans, who think that they will be heard because of their many words. Do not be like them. Your Father knows what you need before you ask him.

It is not our praying that changes God it changes us. The rosary if prayed right is not babble but a contemplation on the Gospel and on the prayers that are said. The reason for the rosary and for life on earth is to change us. As we change we are prepared to receive the gifts that God wants to bestow on us.