From all the pictures I've seen of Nightmare Moon and Luna (those who are not vectors or actual pictures of the show), this one is really amazing and is one of my favorite ones.
Personally, I don't like the taste of Pepsi or any of their soda brands. But now that I've seen this picture, I'm going to give Pepsi another try. If that was the intention of the artist, I must say that he achieved the goal. This image can be a great ad for MLP and Pepsi.
The colors, the background, the characters and the main idea is just amazing. Not only because Nightmare Moon is my favorite character I'm saying this, I really think this is a great piece. And the fact that this is a fanmade work, makes this a true master piece. Great work !