If you subscribe to Met Opera on Demand, or if this airs on PBS, I very heartily encourage you to watch this visually stunning and thoroughly enjoyable work. Do so even if you're not a fan of the Hitchcock movie, or not a fan of modern or minimalist music. At the very least give it a few minutes of your time. If you're like me you'll be quickly hooked and hungry for more.
To me the stars of the performance were the eye-popping costumes, the set design, the very clever choreography (and chorus), and of course Isabel Leonard perfectly and exquisitely cast as the beautiful, bewitching, mysterious Marnie.
Most of the other characters take a back seat to Marnie herself, and act as backdrops or enablers to her odd compulsions -- except for the male protagonist's brother, who acts as an antagonist, well sung and acted by Iestyn Davies.
I thought the score and the libretto were fine for the material -- inventive enough, but never too "out-there" or odd. The score doesn't necessarily excite over the radio, but but viewing via TV, on-demand, or in the cinema, it's perfect, plus following the storyline via reading the subtitles (in modern minimalist opera even English-language lyrics and ensembles are fairly hard to discern consistently) makes the story come alive.
I found this opera magnetic and awe-inspiring. I highly recommend checking it out.