If this was a remake of a French film, then the French film was a remake of "Heidi" from 1937, staring Shirley Temple. The story of the unlikely outsider changing the lives of people who have given up on life in one way or another, is not new.
I think Kevin Hart had to make a believable transition, and walk a line where the audience expected him to be funny, but we soon see he has quite a dramatic side that has to be convincing,while maintaining his ex-con history, and convince Cranston, the quadraplegic who is basically waiting to die, he still has a lot more to live for.
I think Hart's performance was subtle when it needed to be, and Cranston
conveying the complexity of a character using only his facial expressions without being able to move a muscle was fantastic. Those two had the perfect chemistry for the story.
The movie had beautiful cinematography, good editing and was long enough to have time to tell a good story. Just loved it.