This teaser shows a prime example of Strauss's desire in his operas to retain all the minute, febrile orchestral detail of his tone poems at the risk of their being lost behind the listener's inevitable focus on the voices. A gossamer web of arpeggiated themes, gleamed by glockenspiel, twinkling harp and spiraling solo violins, form a tendriling harmonic background against which the vocal line can wander. This is one of several sections of the opera where I suspect the reduced forces will enhance the audibility of this orchestral detail.
Oh, I'm sorry: were you expecting the big recognition bang? Or perhaps Elektra's aria?
You'll have to wait for live performance for that.