Now that there are more pics, I can see a definite problem with the geometry. You've added greebles and things that can be done with normal maps and good textures, but haven't straightened out the corners or improved the base mesh significantly.
For instance, look at the arms that connect the mitts to the main body. At both of those junctions there are some triangles at weird angles. That makes it look less like a real object and more like a mesh built of triangles. With your polygon budget you can do much, much better.
Probably not in SketchUp, though. Its editing capabilities on the vertex level are pretty poor.