The use of color is what stands out most in this piece. A great contrast of warm and cool, with splashes of yellow to accentuate the warmth and keep it there without any frigidness. The background is nicely abstract, with enough complexity to be interesting, but not so much as to detract from the central characters that are the focal point of the piece. There is no clash between the two, letting one shine while the other helps the main part to shine in turn. The characters themselves work together, the male with his cool colors, and the girl with her warm orange, using complementary color to create a connection that makes both characters equally important to the structure.
One of the detractions to this piece is the simplicity of the pose: two characters, abstract background, hint of action, portrait style. Both faces are level with one profile and one 3/4 forward face. The angle of the female's arm is a little awkward where she is holding the basket ball, and the cut at the elbow causes a sense of incompleteness. A good rule of art is to never cut off the character at a joint, especially if it leaves a part of the body floating with no connection to its owner. Putting the elbow back in/adding it might remedy the oddness of her arm, and make the pose more natural when looked at in length.
More pluses are that the line work, while the simple weighted line, do not detract from the color or overpower its impact, which is what comes out to the viewer. There is use of colored line as well, but not too much as to take away from the comic book feel that is manga style.
Overall, a good piece that while there are tiny errors, is a beautiful success.