Great job, there is only one thing that bothers me (not too much actually, but...)
The Mech is well-focused, and the background is blurred, and that's OK, but when the ground meets the foot of the mech it should be focused like the rest of the mech because they are at the same distance... As it is it seems to be almost floating into a 360° panoramic photo applied to a sphere and it's a real shame, 'cause this render could be 10 times better if the BG and FG were using the same DOF settings!
