The image is kind of blurred/muddy at the moment. There
are a lot of seemingly random shapes without too much coherence.
What's with the strange pattern type shapes on the edges of the
foliage on both sides of the image? It looks like random placement
of an enlarged stylised brush. The single shining eye of the mechs
are kind of neat, but I cannot make out anything much about their
design or how they move. I would not have known they were giant
robots unless you had told me so.
Also, cant make out what is in the bottom right hand corner of the
Interesting concept, but I would use this as a launching point or rough
sketch to recreate the image with those issues addressed.
I think you've got a really nice start and an intriguing concept, but I agree that it is quite blurred out. Sharpen up the details on the robots, perhaps add another lightsource to distinguish the elements in the bottom? Also, I think you could add a lot more depth to the painting by rendering the graphics in the top corners.
To the color issue: jpegs tend to compress images a lot, maybe try saving it as a .png instead?