I have just bought a copy of the reprint of these Propers of the Mass, published by the Neumann Press.
Let me first of all clear up the name: this is the work of the Revd Carlo Rossini in the 1930s, not Gioacchino Rossini, the great opera composer of the early nineteenth century. If you were hoping for elaborate coloratura and long crescendos you will be disappointed!
What Carlo Rossini provides is a simple setting of the Proper for every Sunday of the year and every major Feastday, based on the Gregorian Chant psalm tones. The music is set out in modern notation and the words clearly pointed underneath the music. Different psalm tones are used for different parts of the Mass and for different seasons.
Of course the ideal is to sing the whole of the Proper to the chants from the Liber Usualis, but this is a terrific resource for less experienced singers or a group who have limited time to learn and practise some of the more complicated chants.
Having sung in a choir that sang the whole Proper every Sunday to psalm tone 8G, Rossini's work provides a more sophisticated yet simple to learn way of singing the Proper.
I am not ashamed to say that I plan to use it myself! For anyone wanting to have a Sung Mass but worrying about what to do about the Proper - here is the answer.