I really liked this episode. I feel like the characterization for Twilight, Starlight, and Trixie was spot on here. I'm glad to see Twilight learning more about teaching and also learning more about friendship in the process. Trixie wanting to 1up Twilight is understandable, but what surprised me is that Trixie felt bad afterwards and genuinely cared about Starlight. I seriously thought that Trixie was just using Starlight, but what happened in this episode developed Trixie very well and made her way more likable. Then there's Starlight, who can't even seem to make friends in the "friendliest town in Equestria". I'm starting to like Starlight a lot. Not only that, but she reminds me of Twilight in a lot of ways and still stands well on her own. I enjoyed the drama between the three of them and the lesson they learned together. The episode was funny and also kinda heartfelt at times too.
Also, the Derpy and Vinyl thing was pretty amusing. I didn't expect them at all, and that's what made it so funny. It didn't feel too forced, so no problem there.