The smudging on the render looks poorly done and the blending is non existing. The C4D is only half visible because of the smudge, which doesn't work. The lighting isn't proper and the black soft brushing around the edges are to dark. It's missing a lot and definitely missing a wow-factor.
Keep it up, seems like you just got lazy on this one.
Try and work on the depth of the piece also the lighting is not right, could be done better. Not sure if it's the lighting that overlaps the render or some smudging, just looks uneasy though.
Keep it up none the less, smudging isn't easy.