Oh wow. Let me just say first off, time well spent making this pixel. It's incredibly gorgeous, and the highlights along the hooves and especially in the mane and tail make the pony look alive and playful. Definitely adds a lot of luster. I'm very pleased with the color scheme of this pony as well; the highlights were expertly blended together. Multiple tones in the coat and mane make it appear more diverse and like I said before, alive! If I were to say one thing that was wrong with this piece, it would be a few proportional issues that I noticed in her neck and belly. However, this may have just been your specific style when it comes to drawing ponies, or the fact that she is turned at an angle and it wasn't quite right. Regardless, I'm giving a solid 5 1/2 stars on technique, if not for the astounding color alone. Anyway, amazing work, this is something to be proud of, especially with pixel art!
Heh. There's a good reason why a lot of pixel art is small. When you work really large, there are more pixels for you to polish and it eats up your time. Most self-proclaimed pixel artists who work so large tend to disregard pixel-level polishing that's really important with pixel art.