When I saw that this recording was coming out, I immediately asked for a review copy. As best I can determine, Harnoncourt has recorded the Missa Solemnis twice before, and perhaps more. I don't have those recordings to compare to this one, but can find no flaw in this performance.
This recording was taken from the performances at the festivals in Graz and Salzburg in the summer of 2015. It was Harnoncourt's wish that this be his last released recording. It stands as the conductor's farewell to us all--it is both a fine and fitting farewell from a great musician.