The monster looks really puffy, especially in the tentacle thing that's impaling the man. It's because you go from the highlight all the way down to the darkest dark in a sort of radial gradient. It's looking too much like pillow shading stemming from a single point, the highlights, and just going in the pattern of the shape being filled.
This is going to sound confusing, probably, but the back leg of the shaded monster, on the viewer's right side, it looks like it's stemming from a bump in the head, rather than the thorax because of how the head on that side is shaded. Which makes that same leg look like it's in front of the leg that's actually closer to the front of the creature, but the viewer knows that leg is suppose to be behind it, so it's become a sort of optical illusion because of how that highlighted area on the head and that leg line up.