…Weelll… the lighting is too stark and too oblique, resulting in horrible shadow problems. The ground… well, the ground looks like lumps. It isn’t textured or even modeled, it seems like a random displacement map, adding to the impression is that Sephiroth’s foot is actually going through it.
Ok, discounting the searing, saturated, coloured lighting, the background is a low-contrast, muddied brown photo, which makes everything like really disjointed and unrealistic.
The only things that are kind of good about this picture, though they aren’t that great, are the models, and since you ripped them out of the game that says nothing for you. Using the game’s low-poly models probably wasn’t the brightest idea anyway.
Also, you could’ve rendered it in blender internal without any loss of quality, because indigo–like everything else–is only a tool, it isn’t a magic ‘MAEK LOOK GUD’ button. You have to actually put some work into the pictures first.