I am actually not sure what to think of this. The story behind the picture doesn't come until you scrutinise the picture- Both a good and a bad thing. The Lighting is done well, and while there is a lot of detail on the robot/mech subject, enough is put on the surrounding to make sense while not SWALLOWING the subject.
Mechs are very common and unoriginal, but this design is. This design looks plausible and futuristic while not feeling "far-fetched". The dead "campers" in the surrounding hints the mech being one of the bad guys, although I may be wrong.
The use of colour works. Nice and simple.
This is a very good piece.
They say criticism was about hearing what you needed and not what you wanted, but I am pretty sure you got to hear what you need and wanted to ;3
Improvements would be improving details on the background and suroundings, but i believe this piece is good enough the way it is.