Great colour scheme and you did really well to stick to that in both the vector and background. Only thing I'd suggest with the vector is adding a hilight to the glasses on his head. They look a little flat and opaque without some kind of reflection...
As for the background, it's an interesting concept, but I don't think it flows too well. The patterns within the shapes are too sharp and blocky for my liking. Try experimenting with stripes from
http://www.stripegenerator.com/ and see what that looks like. Also the shapes in the top right and bottom left corners seem to decay and I'm not sure why. I'd have a go at trying to keep the shapes constant within the background.
But other than that, very nice work indeed! Keep it up!