When it comes to the issue of Rey being a Mary Sue, I must say that there is a lot of truth to that statement. I like the Force Awakens a lot but this is one of the films biggest issues for me. And Max Landis pointed out something important to this discussion which is that when criticizing the fact that Rey is a Mary Sue, responding with in-universe explanations as to why she is able to do these things does not help your case. Because the issue is not that it doesn’t make sense within the context of the universe. The issue is the direction that the writers decided to take the character. Could you explain away how Rey beat Kylo? Kind of. But that doesn’t matter because from a writing perspective, it is not smart to have your antagonist be beaten in the first film of a trilogy by a newcomer who just tried out a light saber for the first time. Not to mention how she understands the falcon better than Han (that was just ludicrous), learns a Jedi mind trick on the spot, defeats Kylo in both mental and physical battles etc. Rey simply isn’t written as a character with enough trials and weaknesses to overcome. This is why I am slightly nervous for episode 8. I just do not see much growth for Rey from this point onward.