Absolutely breath-taking. The pure dimension that this manages scene manages to acquire is dazzling. The luminescence sparkle of the crystal against the pale, but notable hue of human skin is awesome in force and vision. The shadows are just right, not too dark, not to light. The emphasis well placed. The amount of highlights truly is what makes this stand out to me though. It's as if I could truly believe this was actually taking place in an enchanted cave. It makes the presence of the Unicorn apt for this piece as it fits right in. Again truly remarkable, wonderfully rendered art work. Well done.
This drawing has a story to offer, even if this is just a random character. You have succeeded in making me wonder why the unicorn wants to protect the elf (assuming this is an elf). The color quality is also very well balanced. It is soft, and yet a feeling of power is still evoked in this piece. The details of the flowers, her hair, and the crystal are also well done. I see you have already mentioned that this is your first time drawing a horse figure. I was able to see that there wasn't a clear understanding of the horse figure. It seems as though it's based roughly off of the alicorn from Sailor Moon. This isn't necessarily bad since this is an anime styled piece. But my advice is that it might be better to sketch a horse from life, or from a photograph. Anime-izing the horse from the life sketch may prove to be useful. The drawing aspect of the unicorn is the only complaint I have about this piece. The colors on it is still very well done, and I do like the style of its mane. The expression of the lowered head certainly tells me that it is warning me to stay away. I like the starry glows. They help give the environment a sense of peace, while the characters involved are warning me that I may be disrupting that.
This is pretty good for your first time drawing a horse! Next time, work on the general anatomy a bit more, especially around the face and the mane. Most horses are either right maned or left maned, so just keep that in mind.