Spoiler: S9 Ep4
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So this was the episode all about facial expressions. Cause that's the one thing that really stood out for me. It was pretty funny at parts, but felt like just a decent slice-ish life kind of episode, not a big 200th episode thing. The 100th episode at least jumped out of the box by focusing on background ponies (Derpy, the Doctor, Lyra, Bon Bon...) and their amusing little side plots and trying something very different.

Oh, second thing that stood out for me--Out of that whole unexpected plan, AJ was the only one that succeeded in her part. Point for the earth pony.