My advice is try to get in to the soul of what you are drawing. Try to feel what is going on there. Here I see something like if some big company will slap on some low quality commercial, where people feel offended of what they see. As a long time fan of TMNT I feel the same. Sorry but this is it.
p.s.
I see that you can do better, that is why you are in my fav.
And the abs :S , the 2 stars are for the head. :)

It was hard for me to distinguish the figure of Leonardo from the rest of the background with this. I'm guessing you prefer to use a shading technique for your work, but it doesn't help if you don't give your piece good dynamic contrast. You should study other artist who have know how to use dynamic lighting in their work to help bring the subject material to life. To give you a direction for that, the Spawn comics and various Batman/Dark Knight comics typically used high contrast between the shadows and highlights in a way that still has the figure shadowed in darkness, but not consumed by it that it's hard to see. Additionally, consider perspective and the angle you're viewing the subject. If you're looking down at a subject, consider how you can make that exciting. If you're looking up, consider how the angle changed how you draw the figure. If you're looking straight on, consider where the horizon line is and how you make the benefit your piece.

Put in a little more work, and this will be an outstanding illustration.