Hmm... I like it. Now, personally, I think the part that could use the most work would be the part where she's walking towards the camera. The walking seems a little off, and it's kind of dragged out - overall, the quality seems just a little lower than the other parts. Something else that struck me as odd was that Applejack is the *only* one who didn't get a smile. I mean, I suppose she had good reason not to, but it still felt out of place. Another tiny thing is that, at the beginning, the line in her tail seems to be bouncing out of time with the rest of her tail. And I don't know if this one makes much sense, but the smiles didn't look quite as "smile-ish" as I thought they should. They were a bit too... indistinct, I guess is the word.... Yeah, I'm a real master of communication over here. What I'm trying to say is that I think they needed to be more easily identifiable as smiles.
Anyway, this is largely a review by exception - if I didn't mention it, it was pretty good, if not better. Just make sure you practice lip synching and making the animation smoother and more lively and refine your concepts and yadda yadda yadda, all the stuff you'd naturally improve on anyway, and belt out another gem for us.
Overall, good job!