Alright, this is an awesome picture, for several reasons.
Look at ONE snowflake. I don't know if the perspective pulls in for anypony else, but this is amazing! With me having a lazy eye (Yes, just like Derpy) it really kills 3D movies and pictures and everything. This is as close as I'm gonna get to actual depth perception on a 2D plane.
I especially love the depth of field effect in this work, I always fall for DoF (If you don't believe me, check my gallery).
Twilight looks proportionally correct and her expression is amazing, I just can't help but try to think of what she's thinking of!
Only thing I could see that could use improvement is that some snowflakes are transparent, while others are a dead-white. It can get really distracting in some cases, like the two above Twilight's head.
Overall, this is some amazing and really inspiring work, and I hope to see much more art from you!
You managed to pull off one of my favourite looks for her. This open, curious expression is just wonderful, and this particular pose makes it even better. The background is rather... soft-looking, by way of having smooth lines and subdued colours. Even the mountain peaks appear less sharp than they could have been. It's not a bad thing, however--together, they help make the picture feel a lot cozier and warmer than all the snow would suggest. I like it very much! Well done, maker!
I would've normally placed it in EqD's drawrfiend commentary walls, which I build daily, but with its comment system mysteriously destroyed, I went and placed the relevant comments on the pictures' own pages. When more of your artwork appears there, be sure to look down to the comments. It's likely that I'll have said something about it.