Seeing Chastain's Molly push on through each ceiling she's presented with is enjoyable. Her ability to show confidence and compassion simultaneously is astounding. Of course she is beautiful, but to stop there would be akin to think the biggest part of the iceberg is above the water.
The fact that there is little mystery to the film shouldn't matter if character and feeling are what you are seeking. The reveal at the end is less of a surprise than the action of the climax. And in typical Sheridan fashion the climax is never the conclusion of the story. Time must be taken to recover. That is time where most people live in a world without mercy.