This episode was REALLY good. Pretty much everything Amy Keating Roger's put here worked for the best; there were no distracting sub-plots or time-consuming character cameos; everything was blended together very nicely.
Although her character design was uninspiring, Sassy Saddles was a pretty good one-note character. She may come off as fairly antagonistic of a character through the majority of the episode, but her redemption after all is said and done still works because Rogers deliberately keeps her from acting needlessly mean or callous; instead, she incorporates this into a larger part of her character, establishing she's lost jobs because of this behavior before without knowing why.
Meanwhile, Rarity was in top form. Watching her wrestle with a conflict between creativity and straight-forward money-making was an interesting set-up, especially for Rarity because of how business-savvy she is.
The one downside is the musical number. It wasn't that catchy, and I didn't find it as memorable as Art of the Dress or sweet and elite's song. To be fair, though, the second half of the song was a bit better than the first, and the way it was interspersed with dialogue reminds me of broadway musical numbers in a way.