It's been over a decade since I listened to this piece. I used to have it on an LP -- in Latin, for no reason I can understand. Beethoven wrote it in 1790; that's before the Op. 2 piano sonatas. If people talk about it at all, they mention it as a sketch for Fidelio. But it's a wonderful work on its own, as I just rediscovered this week in borrowing a CD of it from the library for which I work.
It adds to it, hearing it in German. (Though, oddly, the soprano and the chorus disagree on how to pronounce the "J" in "Joseph.") Some of the words still fit today's world:
Ein Ungeheuer, sein Name Fanatismus,
Stieg aus den Tiefen der Hölle,
Dehnte sich zwischen Erd' und Sonne,
Und es ward Nacht!
The highlight is the aria with chorus, "Da stiegen die Menschen an's Licht." If you haven't heard it, you'd recognize it in a second; it's an early version of "O Gott, welch ein Augenblick" from Fidelio. It takes a few listenings to get away from Fidelio, which treats the material even more wonderfully, but this is wonderful music in itself. The first half is just the soprano singer with the orchestra; then the material is repeated with the chorus filling in behind the soloist, in a way quite a bit like the opera.
The CD also includes the Cantata on the Elevation of Leopold II, which I haven't listened to yet, and which I don't recall even having heard of previously.