I'm sorry if I did not watch the episode, but if I had to pick a flaw then I would say that Sweetie Belle's behavior would be what would have turned me off.
Note: It would have only been my opinion, that's all.
I think Twilight Sparkle might have let a friendship problem go unresolved (and Rarity and Sweetie Belle's sister relationship go broken) unless she had to step in if Sweetie Belle and Rarity failed to reconcile.
I have got an alternate scenario for you: What if Rarity and Sweetie Belle had failed to reconcile and make up in the end? What would have happened then?
Correct me if I'm wrong, but I think this episode might have left Scootaloo's future flying status uncertain.
Is it still unclear as to whether Scootaloo will fly with her wings or not?