You did an in my opinion very good job on this picture. What I see first when looking at this is how great the colours fit together. They create a harmony that underlines the peace and the innocence of Twilight here. Also you did a fantastic job in terms of shading. The setting is brilliant (especially the leafs. They are a great addition to the scenery). And props to you doing something really good where a lot of people fail. You added a realistic scenery to a more show-like pony (not that it's show-like, but at least more than the rest) without making it look weird. In fact I think you did it so good that this looks even better as with a totally realistic style.
Soooo. Now to the in my opinion improvable things. Let's start with a detail. The scoops of ice cream are placed in a way that the waffle creates a small black shadow which I think is rather unnecessary there. Also the yellow one is hanging over a bit too far comparing to the consistence it must have if part of it is already smelting. The same goes for the red one too. Another detail (where I'm not sure if I should see that as your style) is that you've given her a purple tongue. Good. Next thing is her arm (not sure if I should call it arm or leg). It's too small in relation to her body even if she's just a filly. (Here's the reference i'm refering to [link]) The last point is her tail which looks kind of flat. Probably because the lightning goes through the whole tail without losing a noticable amount. ( And here is everything i mean marked (tongue and ice are edited as far as muro lets me do it)[link])
All in all it's of course a wonderful picture which you can be proud of ^^