Well, this is sure one of your best drawings so far. I really like the background, the shading is great and everything is just very nice looking.
Vision: You really hit the purpose, to show Octavia. The colors of the background really fit with her eyes and the band around her neck. Also the clef is very fitting with the main idea.
Originality: As always I would recognize your style out of hundreds. You really have a very special kind of making your drawings. But I have to remove a half star, because the idea of making an Octvia-picture isn't really new. If I could, I'd remove a hundredth star, and not a half, but that's unfortunately not possible.
Technique: Do I really have to say something here? You just know how to make a good drawing. Her mane is great, the shading is just perfect, the eyes are awesome. You just know how all that works, and this is easy to see. Great work
Impact: This is kinda personal opinion, which is also kinda important in a critique. I'm just not a big Octavia Fan, but there was a big "WOW"-effect, nevertheless.
Okay, afterall I can say, this is a very very awesome work of yours. Not perfect, but there are not a lot perfect drawings, so this shouldn't be discouraging. Use it as motivation to become even better than you already are, you are even now one of my favorite artists, and one of the best I know.