This is also a pretty well inspiring picture. I'm not that familiar with Gorillaz, but certainly know that they're popular. I just love how gritty this guy looks. The use of colors is just wonderfully done. It seems like you really were trying to imitate a rainbow in this. There seems to be a bit of white which isn't usually there.
Of course, I don't know much about the science of colors. I imagine he's supposed to be a general of some sort. Maybe he's meant to look like Che Guevera? Single figures like this are good if they're drawn well. You succeeded in that.