The Mass according to the Use of the Ordinariate was first publicly celebrated in London last October 10 by the Rt Rev Monsignor Keith Newton, Ordinary of the Personal Ordinariate of Our Lady of Walsingham. The Mass which substantially incorporates the Anglican Book of Common Prayer and the Roman Rite, was the result of more than 30 years of efforts to include Anglican use within the Roman Rite first in the Catholic Church in the US and with Anglicanorum coetibus, through the Vatican's Anglicanae Traditiones commission. The Book of Divine Worship (BDW) which includes much of the American Book of Common Prayer, provided the example of how Anglican liturgy can be successfully incorporated into Roman Catholic life.
However unlike the US Anglican Use, the Ordinariate Use includes options from the Tridentine Mass. The Ordinariate Use also has several differences from the US Anglican Use since the latter drew much from the Episcopal Church's 1979 Book of Common Prayer. In fact the BDW can be considered as a successful effort to incorporate the Episcopal Church's liturgy to Roman Catholic parish life in the United States. The Ordinariate Use draws more from the earlier Anglican Books of Common Prayer and restores much of the usages (some derived from the pre Tridentine Roman Rites) of classical Anglicanism. As a result of the liturgical movement beginning in the late 19th Century, Anglican liturgies incorporated prayers from the Eastern Church. The Ordinariate Use, removes many of these usages proper to the Eastern Church and restores the older Latin usages in the Mass.
Ordinariate clergy are not required to exclusively use the Ordinariate Mass but will have the option to use the Ordinary Form and Extraordinary Form of the Roman Rite. However, Ordinariate clergy will be expected to be familiar with the Ordinariate Use.
How the Ordinariate Use will be accepted in the US Ordinariate will have to be seen. Many parishes in the US Ordinariate and the diocesan Anglican Use have been accustomed to the BDW which has been used for 30 years. Another question is whether the US Anglican Use will remain a legitimate option in the territory of the US Catholic Church.
Photos of the inaugural mass can be seen at the UK Ordinariate's Flickr site.