The movie was held back for such a long time after it was finished. So, there has been a bad feeling about the movie amongst the fans of the book.
There is no reason for the movie to be long and slow as the book was neither. It is heartbreaking because you can see that everyone involved in the movie has poured so much into it, and gotten so little out of it. At least it is not a disaster like "All the Pretty Horses".
if it was a hindi movie, same story, same everything, it would have got 1 star from the same critic. they are biased for firang films. They like to smell their shit.