The first is what it does not do. It does not widen the indult for Mass in Latin according to the 1962 Missal; it does not even require that the currently normative rite, set forth in Paul VI's Missal of 1970, be offered in Latin in addition to the vernacular. Indeed, it does not impose any new requirements or broaden any old permissions. It expresses some of the Pope's wishes and makes suggestions. Regarding Latin:
62. ... In order to express more clearly the unity and universality of the Church, I wish to endorse the proposal made by the Synod of Bishops, in harmony with the directives of the Second Vatican Council that, with the exception of the readings, the homily and the prayer of the faithful, such liturgies could be celebrated in Latin. Similarly, the better-known prayers of the Church's tradition should be recited in Latin and, if possible, selections of Gregorian chant should be sung.
Notice: "could be celebrated in Latin...", "should be recited in Latin." No orders are given; no penalties are threatened. It's all very collegial and seeks to lead by persuasion. I believe there's a very good reason for that. If orders and penalties had been issued, all the media attention and therefore most of the attention of Catholics would be on them, not on the theology set forth in SC. The theology, and the personal example based on it, need time to sink in first.
It will of course be objected that nothing will broadly improve the currently dreadful state of liturgy "on the ground" until the appropriate orders and penalties are issued. That might or might not be true; I suspect it is true; but even so, the tactical approach being adopted by the Pope is sound for the time being.
The other thing I like about SC is the similarity of its title to that of this blog, and the difference of its title from that of this blog. In adopting my title, I had originally meant to allude to authoritative papal documents about sexuality, reproduction, and other "life" issues published since Vatican II: Humanae Vitae, Donum Vitae, and Evangelium Vitae. That's because I've long thought that the "pelvic issues" are the main spiritual salient in the world today, including and especially among Catholics. The spread of sound doctrine and praxis in that area seems to me to depend on a vision of human sexuality as sacramental in both a broad and a specific sense. And I also count on people getting the pun on "life." But I've come to realize that the cause of truth and righteousness in this area depends, among other things, on a better appreciation of that sacrament which is the "font and summit" of the Church's life. For that and many related reasons, it is the sacrament of charity par excellence. There is never too much of either the sacrament or charity. The more we appreciate the former and are accordingly animated by the latter, the more progress we'll make on the pelvic front.