Firstly, I'm going to repoint out the missing cutie mark. Not really your fault, but just to get it on here. Her face is a bit too human, especially the eyes, and the way you fit the hair with them. And, y'know, the whole body shape. Also, since when would she be out there without a scarf? Mittens? Socks?
Enough negativity. It really is a cute winter piece, and I love snow with a burning (or perhaps freezing) passion. My only suggestion is to make your ponies more pony and less human. Keep up the art, and don't let me discourage you.
Squidcrab is correct in saying she looks human — like a cross between MLP:FiM Fluttershy and Equestria Girls Fluttershy — but I assume you meant to do that and I think it's a valid concept. I don't have anything negative to say about it. The overall effect is pleasant.