I love your style, though there is always work to be done.
The main portion of the piece is well done, good detail, and the face of the enemy(?) soldier is pretty sick.
Some minor notes;
The grass seems to be rather slapped on, it pops out of every spot it's placed.
I'm a huge fan of minor detail, so don't take everything I say to heart as your art is quite well done.
The weapon the human soldier is dropping is rather bland, it appears to be a bring with a trigger on it.
The broken wall has no notion of it being a part of anything, add some rubble or other broken bits behind and in front to indicate a city or building.
Lastly the background is a little off, the fire seems to stand out amongst everything and thus leaves the image lesser than it could be. You might add flaming vehicles and other such things to give the image more.
You might consider making a comic, your style would make it very entertaining to read through, and your creativity would make for a very interesting read.