There’s a wonderful background on the history of the rosary at:
newadvent.org/cathen/13184b.htm and another great article here:
chanttherosary.com/rosary-history/ and yet another here:
personalizedrosaries.com/history.html
St. Pius V, himself a Dominican, was responsible for establishing the Rosary in the form in which it was known for several centuries, until the Fatima prayers were added (I’m sure with much grumbling from those at the time who were sceptical of the apparitions). Even the “Holy Mary, Mother of God, pray for us sinners now and at the hour of our death” part of the Ave Maria was part of the original prayers and variations on it existed long enough to be recorded. A personal favourite of mine is “Holy Mary, Queen of Heaven, sweet and faithful, O Mother of God, pray for us that with the elect we may look upon you.” (Sancta Maria, Regina Coeli,dulcis et pia, O Mater Dei. Ora pro nobis ut cum electis te videamus.)
The bottom line is that it’s a private devotion, and as long as the prayers that are said and the mysteries that are meditated upon are in keeping with the Catholic faith, I don’t know how any Catholic could possibly criticise it. I personally prefer to chant the Rosary aloud in Latin according to the Gregorian melodies while I mediate in English (I wish I were fluent enough to think in Latin rather than translating into it and out of it, but I’m not). I would never condemn someone for speaking the prayers in the vernacular, though, or for praying it silently in their head. I used to do that on the school bus on the way to school, using my fingers instead of beads. I’m sure someone will find flaw in not holding an actual physical set of beads as well, but I figured that it was better than not praying the rosary and avoided the distractions caused by taking rosary beads out on a school bus.