It just doesn't look finished.
Try working with smaller sig sizes till your compo gets better. That's what I'm working on right now. I was having trouble filling in a lot of space, so I decided to just work smaller.
Also remember not to rely on one effect too much. I notice you using a lot of C4d's, which is fine, but don't get addicted to them. Use them for effects and lighting, don't let them become the sig. (Unless your focal IS a c4d.)