I'd call it a good not perfect movie, like a lot of movies based on plays. The ending was amazing imo. I might have given the Oscar to Colin Farrell but either way I'm happy it wasn't another musical biopic performance.
In terms of the role of the daughter Elie, Charlie is refusing to go the hospital as without health insurance it would cost a lot of the 100k+ he's planning to give to her after he dies. On the other hand, I question whether this is redemption or just the easy way out and a way to feel better about himself as he dies, which he probably wanted to anyway (I think "The Whale" his Ahab is trying to kill is really depression, not his eating problem). Living, losing weight and redeeming himself by being a good father to his daughter is harder. The thing Elie probably needs more than money is emotional support and the ONE person who believes in her instead of thinking she's a devil spawn like her mom. Otoh Charlie could also be somewhat naive just brushing off some of the nasty things she did like making the facebook post about him, and telling himself that she was trying to help rather than hurt the religious guy. He gave that kid a little too much credit as well and ended up seeing a nastier homophobic side of him, although by the end totally didn't give up on him.
Overall I think there is a lot of interesting character dynamics (I didn't mention Hong Chau's character who is enabling Charlie, and an angry person), but I credit a lot of it to the play which I'm sure is great, I'm not sure I totally love the mix of Aronofsky's style and the material compared to if someone took a relative low key and stagey approach. He made the film feel dark and claustrophobic which paid off at the end when the light was used for the ending, but I'm not sure how I feel about affecting the whole film just to get a better ending.