What is changing with the new mass translation?

The new mass translations are rooted in scripture and from what I understand are bringing back pre-Vatican II language in at least one part, most notably during the Ecce Agnus Dei where we say "Lord, I am not worthy to receive you" we will say "Lord, I am not worthy that you should enter under my roof."

The most common change is when the priest wishes us peace in several parts throughout the liturgy instead of responding "And also with you," we will respond "And with your spirit." This is based on two scriptures: “The grace of our Lord Jesus Christ be with your spirit, brothers. Amen” (Gal 6:18) and “The Lord be with your spirit” (2 Tim 4:22).

Some changes are very minimal like saying "O Lord" instead of just "Lord" before the Gospel. Other changes may be harder to become accustomed to like the fairly significant changes to the Gloria, Nicene Creed, and Apostles Creed. The Nicene Creed throws in a word that's hard to pronounce and probably understand for most people hearing it for the first time; consubstantial replaces "one in Being." For more information on these and other new mass translation changes we have several resources available to guide you and ease the transition beginning this Advent 2011.