Oh god I love this piece. The only one bit that I feel could be improved is your coloring. But anyways, first onto the good points. Just looking at the drawing itself, I must say that I absolutely love it. Everypony's facial expressions are just how I'd imagine them. I especially love Tavi, Lyra, Bon Bon and Berry. So again, brilliant job there.
The only bit that I feel could be improved is your coloring. Maybe it would be better if it was a tiny bit neater and more consistent? And the backgrounds seem a little... cloudy. The stereo on the right hand side is a little unevenly colored. And I think it's a crowd of ponies in the center. But the size of the blobs are a little out of proportion, given that Vinyl is larger than them and still further away.
Overall, I must say you've done a very good job, and I can see that you've put a lot of effort into this! Keep up the good work!