Background- Amazing. Great use of textures and great depth that moves outwards to the foreground. However, there could be more to the right.
Text- Don't like the white text, you should have used the blue text behind the render as it looks spectacular, the little I can see of it and weave it around the render somehow.
Render- Blended very well where it should be while his upper half sticks out. Looks fantastic. Render effects are crisp and clean.
Lighting- Looks good in the center but could have done with a blue photo filter to make the sides look better.
Colouring- Similar to above. Should have made it more blue imo.
I'm not giving you enough credit there, it's a fantastic wallpaper. Keep it up!