Wings I'm not trying to be harsh
This piece would be excellent if there was a greater variation in tone. Whilst art is subjective, and that you can make anything you want to - you have be be careful to not make the work too plain, so here is some things you might want to try:
1) Scan your work. These photos are pretty poor and any decency or tailorship in the work is lost because of the resolution. Scanning will greatly improve how this work looks
2) Shading. Whilst I understand it isn't easy to learn, the only way to get better with artistic methods is to practice. So just say 'hell with it', and shade it. You might destroy it, but you might make it better! One piece of advice, don't be afraid to really press hard whilst shading. When pencilling I normally break quite a few leads. It ensures depth of tone.
Hope that helps. but its real important that you try to make your pictures deeper!