The "While We're At" section of the January edition of First Things contained a good look at the power of the revised Confiteor:
We are pleased, as you can imagine, with the revision of the Mass that began to be used on the first Sunday of Advent, for all the reasons Anthony Esolen listed in “Restoring the Words” (November) and others. But if we could quibble, we really wish the revisers had not kept the Kyrie as one of the penitential rites.
Nothing against the Kyrie, of course, but the Confiteor says more and says explicitly what sinful people need to say. (And besides, when you say the Confiteor you then go on to say the Kyrie as well.)
Here are the words: “I confess to almighty God, and to you, my brothers and sisters, that I have greatly sinned, in my thoughts and in my words, in what I have done and in what I have failed to do, through my fault, through my fault, through my most grievous fault; therefore I ask blessed Mary ever-Virgin, all the Angels and Saints, and you, my brothers and sisters, to pray for me to the Lord our God.” The people smite their breast as they say “my fault.”
It begins with “I,” for starters, with everyone taking responsibility for his own sins, when the Kyrie offers statements about Christ—all true, of course, but not so effective an act of repentance as having to say “Yep, I did it, all right.” Then that “I” confesses that he’s sinned and admits that his sinning is his own fault, indeed his own most grievous fault, and smacks his chest while doing so, which drives home what he’s saying. He finishes by asking everyone from the Mother of God on down to the people he’s standing with to pray for him.
This, we insist, says right out loud what the sinner needs to say as he begins Mass. He’s got to lay his cards on the table, for his own good, and the Kyrie by itself doesn’t force him to do that. The Confiteor draws him into a community, of the saints in heaven and his friends on earth, and particularly the people around him. It reminds him he’s not alone in his sins, nor in turning to God for forgiveness.
And there’s one other benefit perhaps only converts notice so clearly: The Confiteor is an overtly Catholic prayer. You don’t say this prayer anywhere else. It helps you remember who you are and who you’re with, and why you’re there and not somewhere else. That’s not the primary reason for saying it, but in an age of doctrinal indifferentism, it’s still an important one.