Ahhh, now I get why people are talking about Derpy. Because of the line "What should our favourite background pony be doing?" Heh.. well.. that was actually a nudge towards AJ... Raining muffins sounds nice though ^^
It would appear that there is a classic wobble common seen in traditional frame by frame, however some element do not change form all that much (e.g. Fluttershy, Rarity, and Twilight's bodies. I applaud your use of clever yet simple tweening (or frame by frame easing) while keeping everything alive with the jitter from the repeated frames. Congrats, you've earned the watch!
Yeah, but with the aid of computer software, you'll find that sometimes people will stick to a single still image instead of having it flash back and forth between two separate ones. In any case, it suits this, and I expect to see moar amazing stuff like this in the future from you. c: