Nice work! The drawing factor to this image is the style and clean linework, though it feels lacking dimension/depth. As a stylistic illustration it's quite good (if somewhat lacking in visual interest, which an environment or different lighting or more ambitious poses could fix), as a digital painting it could use more 3D form and lighting depth. Overall though you've done well and as a painting exercise you should feel it successful, and continue practicing! Its clear you have skill, so keep it up!