This is me:
It leads with the complete text of his central work on the topic, Spirit of the Liturgy, and then collects all his papers and homilies on the liturgy in several sections: Typos–Mysterium–Sacramentum, Celebration of the Eucharist, Theology of Church Music, and Further Perspectives. It’s listed as volume 11, but published first at Benedict’s request because of the importance of the subject. There are new introductions and editorial notes.
The production is outstanding, and even a for die-hard Ratzingerian like myself much of it is completely new to me. Can’t wait to start it, but I’m finishing In Search of Sacred Time: Jacobus de Voragine and The Golden Legend by Jacques Le Goff, and this is one to savor. I’m hoping his Biblical work is next, since that was a major focus of my study.
My edition appears to be current and corrected. Some of the first run had pages printed in the wrong order (hence the low reviews on Amazon).