This will be my first critique, but I'll try to make this fair and square.
Honestly, upon seeing this, sad-looking Applejack, it really gave me this 'shock' factor. Looking down with sadness really made my heart sunk, literally. It's like, not many bronies out there really like Applejack, or plainly say "Applejack is best pony". I honestly feel like hugging her in life.
While there is nothing much to comment on the vector itself, I suggest that you should remove Applejack's hat, as most people would remove their accessories (Glasses, hat etc.) while being depressed. Or maybe add tears to the vector. This will seriously add more impact to the viewers. I've seen sad ponies and the tears just drove me crazy; I cried. Yeah, I cried.
Overall, nice vector! I really love it! The crisp borders look amazing! Maybe you should add a shadow so that if Deviants want to use this, as they won't have to trouble themselves adding shadows. You could add-on from my suggestions or maybe not; ultimately, it's not my artwork, it's yours.