This is my latest work. Done in Blender Cycles (1234 samples)and retouched in Gimp.
Hope you like it
Great shot , just a question:the dof is a postprocess?
Yes, it is.
I think is the weakness of your nice render
Is the ground a bark texture?
I would tend to agree. Generally DOF is a gradient from crisp focus, to sort a blurry, to blurry shapes. in you picture, the blur is very binary, in that it starts and stops very abruptly, which is not the way the human eye sees. try looking up how to do DOF in camera for Blender, and then accentuate it in GIMP later if you want to add to it.
A concrete one.
Great… How many samples