Usus antiquor (older usage) is sometimes used to designate the Tridentine Mass, which was the form of the Mass used by Latin Catholics from the time of the Council of Trent until the development of the Paul VI (or Novus Ordo), which is the current form.
I usually attend the Tridentine Mass these days. While I can understand how the use of Latin and the sheer baroque-ness of the ritual can be alienating to some (from what I understand, part of the motivation behind the Novus Ordo was to boil the Mass down to its basic elements and make it more accessible to the layperson), there is a mysticism to it which is often lacking in celebrations of the Novus Ordo. Now, the mysticism of the Catholic and Orthodox forms of Christianity is primarily in how the symbols become the things they symbolize; these are the sacraments; contact with them is direct contact with God.
The Mass is the ultimate form of this, so to speak. It memorializes the Crucifixion and it is the Crucifixion. And it offers the most extreme and intimate form of contact with God: eating Him. This goes way beyond a face-to-face encounter.
To actually have a liturgy which does this is both amazing and frightening. That we feel the need to brush it up with tacky 70s hymns is a tad incredible.
…aand I’m starting to realize that I’m not up for getting into serious liturgical controversy tonight, so I’m calling it quits now. Here’s a brief clip I found on youtube: