the wall on the left is too vague, nebulus. value problem,,,,maybe color also. it blends too much with the arch, which may be better off popping out. unless you did it on purpose,,,like a time warp entrance or something. color change may be a good solution,,,it'll add punch to your blue/yellow. the areas of blur along the edges of the arch bother me...they look like mistakes. if you did them on purpose, push the idea.
i would lighten the ground shadow value in the distance, so it doesn't look like the foreground shadow value.
are you trying to accent the thumb or the hand???
here's and idea to give your piece more mystery.. put the whole head in shadow. make it just a dark silhoette. you don't need all that head detail anyway. tilt the head away a tad so you get more profile...that way , if you sihloette it, the profile will give you more form.....milt
"he who thinks he know all and knows nothing is king in a kingdom of one,,,,,or a critic" - the kobe