I wonder what people here will think about Korngold opera the "Dead city"
It's a bit like drowning in syrup :)
In small doses I like some of the music from this opera, but I find it hard to sit through in its entirety. I think the principle problem is a very shallow plot, in which nothing really happens. A man misses his dead wife - and then doesn't. It's hardly enough to fill 2.5 hours in a theatre. The librettist needed to have included a subplot involving one of the characters, to add a little variety.
Of the German operas of that era, I greatly prefer Krenek's JONNY SPIELT AUF. In fact the two operas were competing for a stage production in the same year - Korngold's family connections helped him win this little battle, whereas Krenek was a foreigner regarded with suspicion.
But JONNY is a much better-written piece, not least because it has a well-shaped, interesting libretto with a double plot... the romance of the composer with the opera-singer (with its setting in an alpine resort at the opening, a nice touch which offers the composer a chance to write atmospheric music), and the fight for the Amati violin between the great maestro and the negro jazz-man (with the chance for Krenek to write the jazz-band into the score as a self-standing entity). There's also a philosophical undercurrent about whether European art-music is a dead duck, and jazz is the heir-in-waiting?