There is a very consistent art style here, and it's a very good one. It's fanart that isn't 100% derivative, which is hard to pull off.
The facial expressions not only perfectly portray the emotion listed, but they also show how uniquely the character in question would show each emotion. Pinkie Pie is the kind of character to have very over-the-top and visual emotions, and this captures that feeling very well.
In addition to managing the more visual emotions, it also manages to capture the more subtle emotions very well. Each subtle emotion is presented in a way that they are clearly distinguished from each other, something that's hard to accomplish using any character, let alone a character that normally has such loud emotions.