Lemme start off by saying that I adore your art style. It's vibrant and colorful, and very much in the style in the show, while still being original enough to call your own.
Derpy's arm looks a bit odd in the last panel, however, though that's probably just nitpicking on my part, and I'll chalk it up to the cartoonish style.
Now, while the art of this comic is wonderful, the joke...well, to be blunt, it's stale.
It's not that it's bad, it's just boring. The punchline is literally, "Derpy loves muffins", which has been absolutely done to death a million times over within this fandom. Vinyl's reaction doesn't really seem to fitting either. She looks like she's utterly heartbroken, which I find is a bit of an over reaction to a friend disliking a restaurant.
In short; good art, poor joke.
As far as what you said about the joke, I believe it still had good potential despite the concept thereof being overused.
But I do agree with the part about Vinyl's reaction
THANK YOU for not giving it 4, 4.5, and/or 5 star ratings on all the categories like most critiques feel like they have to do or else they'll offend the artist.
I feel the originality rating was a bit low though, it's not like it was a complete copy of another work. It's an original scenario, so I would have given two stars for that at least.
People, it's okay to not give 4-5 star ratings all the time. It's what all five stars are for. No[t all*] art is perfect.
*Some may say no art is perfect. That's debatable. Some might be a perfect representation, but not all art is perfect, that's for sure.