Wace's Roman de Brut is the oldest extant Old French text concerned with the legendary ancient kings of Britain, and this makes it a work of extraordinary literary importance. It is a work in the Galfridian tradition, i.e., the tradition of legendary history started by Geoffrey of Monmouth with his Historia regum Britanniae, and the second most important work in that tradition after the Historia itself. And even more than the Historia, it is one of the founding texts of the Arthurian legend. For instance, it is the first known text to mention the Round Table. Written around 1155, it would then go on to have many imitators, some of which had further imitators, slowly morphing into the Arthurian legend recognizable today.
We have had Wace for the fortnightly book before, reading the Roman de Rou (under the translated title, History of the Norman People); but that text seems very much to have been one he did not enjoy writing (at least, he repeatedly stops to complain that he is not being paid enough). Here, I imagine, we will get the great Norman author from Jersey in a less cranky mood.