Wicked!
I love the use of color and the almost undersea vibe it gives off. The character you've portrayed, which is my favorite aspect of this drawing (not to say that the background isn't equally as stunning), is very dynamic. That is, the character very much has it's own anatomy and is, in that perspective, a believable figure. In turn, the background also adds to the reality of the drawing. Despite having thick, black, cartoony lines on your character (which are awesome, mind you), the drawing sustains a vague sense of reality.
The composition itself is entirely amazing. Overall, there are no major flaws (unless being mindbogglingly stunning an art piece would constitute as a flaw).
I've seen some of your work before and it is absolutely brilliant. Might I ask, what did you use to color this piece? It appears to me as if it were done in photoshop, but you've either done it so skillfully or perhaps it's that it's in a different medium, because there is no trace of the telltale digital brushstrokes that so remarkably denote the use of photoshop. In a sense I think that adds to the beauty of this piece as well. Anyways, I love your art. Cheerio!