Sisterhooves Social boasts some effective character development that shows off better than any of the previous episodes S2's new direction. Where S1 had a focus on friendship and learning about base friendship lessons, season 2 has a further focus on individual character development and a broader range of themes. There's clear evidence of that here as Rarity develops as a character. However, it's offset by some issues with the execution.
The main conflict here is between Rarity and her sister Sweetie Belle, and one thing that bugged me was that it started off with Rarity clearly being in the right. There's the vague implication that getting annoyed at Sweetie Belle for her mistakes is the wrong thing to do, but from my perspective Rarity's entirely correct here. As the core conflict is that Rarity and Sweetie Belle aren't properly conceding to each other in their relationship, these incidents come off as a bit unbalanced.
However, the core of the conflict itself is strong enough, with clear evidence later of the two sisters making a bigger fuss out of their disagreement over Sweetie's mistakes. At times these seem slightly desperate, but for the most part they work to set up the story's resolution. As a result, the character development here is effective, with Rarity and Sweetie Belle learning about conceding more in relationships. It's a fairly effective lesson that has applications outside the stated sisterly relationship.
There are a few funny moments here and there, particularly at the beginning, but as the episode goes on there's a bit of a shortage of effective jokes. The ones that work are quite good, but the episode seems to not have humour as its focus. Unfortunately, this is compounded with a slight lack of energy, especially compared to the previous two episodes. There's far less going on, to be fair, but coming off of the very energetic Luna Eclipsed, the episode isn't particularly exciting. There's moments where it's fun, to be sure, but it's a less entertaining episode altogether.
Altogether, Sisterhooves Social is not one of my favourite episodes of the season. Maybe I simply couldn't relate that much to this problem, but it didn't grab me as much as other episodes. Despite that, I think it's a pretty good episode, as it boasts some good character development, and a strong main conflict that some might be able to relate to. It's a good episode.