Specifically compared to the book? The movie fails in every capacity as an adaptation. The book is a lot clearer that a god that would require brutal human sacrifice to avert an apocalypse is an evil god. One that shouldn't be obeyed. The entity that is glimpsed in the light has a malevolent aura. And in the end it's about two people choosing to live on after their world has ended, suffering unfathomable loss. To go on regardless of what happens because all you can do, is go on.

The movie is 'Yay, human sacrifice! 😁'. Okay, well maybe not quite, but it never deals with the moral complications the plot raises.

I think the film is well acted, it's shot beautifully. Shyamalan directs the hell out of it, but it's lack of thematic coherence in the writing is a fatal flaw.