Maybe it's because I'm just partial to the color blue but the varying tones draw my eye to different parts of this piece which I do like but because of its abundance it can be a little distracting. The sparkling white marks you have are a nice touch, however, like the blue, there is too much of it for the eye to follow and takes away from your artwork. The problem area for me is the wings. The pony's overall darkness is cool but I think it'd be better if you lightened it. Total black doesn't feel right. In general I really like this piece. Her mane and tail are elaborate but simple in design with a very unique pattern. It shoes that you put a lot of thought into the placement of each band of color and I can definitely appreciate the vision. Well done.
Hmmm... At first glance, it's one of the most beautiful ponies I've ever seen, and even after examining it, it still is. But I have to agree with PC on a few things. The sparkles and embroidery are extremely bright and distracting on the pure black of the pony's coat. What's more, it seems to be heavily emphasized on the back end. Meanwhile, I can barely make out any details on the face; I have to literally squint to see them. I'm also having some troubles figuring out if this is a mare or a stallion (or a colt or a filly, for that matter). The hair would imply a mare, but the body and face structure seem a bit masculine to me. Age is another fact that gets me with almost all OC ponies. I'm not sure if those dark symbols that look like feathers surrounded by the sparkles on their flank is a cutie mark or not. If it is, then it needs to stand out more (I can barely see them).
Still, with my nitpicking done, I have to say it is still a very beautiful and very original idea for a pony. Your art style is extremely detailed and extremely close to the show's official artwork. Honestly, I think they could go on the show and look completely natural. I adore the colors, even if the black needs some more contrast on the details and such. Good work all-around. ^.^