[Taken from NLM]
With such an important development in the Church, it would seem appropriate to "count our blessings" by quickly summarizing the PRE and POST Motu Proprio scenarios as we can now see them.
PRE-MP: The 1962 Missale Romanum generally thought of as abolished/abrogated -- even though debated by some in small circles.
POST-MP: The 1962 Missale Romanum clarified to have never been abrogated.
PRE-MP: The 1962 Missale Romanum an "indult" or special exemption to normative law.
POST-MP: The 1962 Missale Romanum a 'normal' liturgical use of the one Roman rite.
PRE-MP: All public or private celebrations of the 1962 Missale Romanum required the approval of the Ordinary. Ditto for other sacraments.
POST-MP: All public or private celebrations of the 1962 Missale Romanum (and associated sacraments) are left to the determination of the priest; the faithful are empowered to approach the priest for it and use the Bishop or Ecclesia Dei commission for appeal if need be to have their request fulfilled; priests and bishops are effectively asked to comply or to bring in any resources necessary to help do so.
PRE-MP: The 1962 Missale Romanum "frozen" in its development, "as-is".
POST-MP: The 1962 Missale Romanum "unfrozen" allowing, through the direction of the Ecclesia Dei Commission, organic liturgical development to resume. Possible addition of new prefaces. Allowance for option of direct usage of vernacular for Epistle and Gospel readings.
PRE-MP: Personal parishes may be setup by the bishop for the concentrated use of the classical use of the Roman rite. Clergy from such groups may also be brought in to offer said use.
POST-MP: Ditto. That remains the same -- though again, not in replacement of its use at any or all other parishes it should be reminded. It is not a matter of "we have a parish for that, we don't need it elsewhere."
The above are what we might consider the juridical issues of a pre and post MP Church.
But there are also issues of catechesis to be found here. Issues that weren't juridically or formally so, but what we might call issues of confusion or 'perception' with regard to the classical use.
This MP contributes to a clear clarification on the following misperceptions:
PRE-MP: 'Popular' perception of the classical use as being outside of normal parish activity. Often limited to Sundays and sometimes Holy days. Faithful often told to go to "their parishes" for other sacraments.
POST-MP: Affirmation of the use of the classical use for weekdays, Sundays, solemnities, special-event or 'one-off' liturgies, as well as the ability of the priest to use any of the previous sacramental forms. Further affirmation of the use of the classical liturgy is also fine for public parish liturgy, while keeping sensitive to pastoral considerations. It need not be "special" or merely private in that regard.
PRE-MP: 'Popular' perception that the classical use of the Roman rite was either, "not encouraged" or seen as pseudo-disobedient, or anti-Conciliar.
POST-MP: It should be clear now that adherence to such is not anti-Conciliar as the Pope has pointed out. Moreover, it cannot be understood as "not encouraged." It is a normal, extraordinary expression of the Roman rite.
Overall, the significant, general shift in the post-MP Church is of course the de-marginalization of the Roman liturgical tradition and a re-assertion of a hermeneutic of continuity.
Clearly, the document is an important development for both those attached to the classical use and pursuing the reform of the reform.