The model and texture looks very nice in the zbrush screenshots, but the final render (the one at the top - if it's the final one) is just not right, sorry.
-something is wrong with scale - either the frog is 2m long, or the plants are tiny - yet the plants do not look tiny, they look like normal scale ivy, and the grass looks like normal-sized grass
-the blurry background should probably be more blurry if it's a macro shot
-at the background photo sun is clearly shining from the back, yet the lighting does not represent that, and there is also a strong specular from behind the camera, like a flash, which looks really bad, I think good lighting could greatly improve the feeling of the scene and mask some flaws
-the bottom of the image - what is it? a flowing river? it looks like it was taken with long shutter speed, so it could look good if you matched that with your 3d objects - for example motion blur in some places - the frog's leg maybe?
-stretched textures - which strangely look pretty good in the 3d screengrabs
-materials - everything looks like plastic, especially the plants
