I think that's a significant improvement. Chani being "ride or die" in the books is an awfully charitable way of saying that she basically has no purpose to her existence outside of Paul. The movie choosing to have her really show some resistance to the shitty / crazy stuff he's doing gives her more inner life as a character. It also nicely sets up for Messiah where there's definitely some tension between her and Paul (though never sufficiently explored IMO) over his choice to make Irulan his wife.