My advise is to start adding subtlety to the map. Try setting various layers to 75% opacity (or perhaps less in the case of the labels) and see how it appeals to you. Look at colors with an eye toward how they interact with other colors near them. I'm colorblind, so when I see color issues, they either aren't there or they are there pretty dramatically. The color of some of the larger labels puts me off for some reason.

I think it's a lovely map and with some fine tuning can become a solid piece of work.