The arm is blurred The render is overly sharpened while the lighting makes the arm appear blurred, it's too bright, the tentacles are going over the focal, and the tentacles ruin the flow. You shouldn't have used the brushing/paths tools for those tentacles, as they really ruin the image. You should've used the paths tool to try and give it a flow. Remember, you can have foreground effects overlap the render, but never on the focal, the face. What you really needed to do was make a new layer from visible, then go to color > brightness/contrast, then lower the sliders a bit to your liking, but never this bright. The render's orange color really clashes. This is where a gradient would've come in handy. Or at least you could've made a new layer, brush over the shirt in green, and then set it to color. Even with that fixed it would've made it monochrome. Just green, green, green

The only thing you really did good in this image was the background effects on the right side. This one needs improvement, I don't see why everyone is telling you it's so good.