@nessillustration
It's really a beautiful world build/map! I don't think I have any constructive critique on it, because the colors all communicate well, and it does what it is supposed to do really well - gives direction. And from what I've seen of your work, it really fits in well.
Also, I'm not working in the field right now - so take this with a grain of salt. I think there is a place for illustrations like this in portfolios as well as in children books. @smceccarelli just posted an image/client piece where the values were meant to be subdued so as not to draw too much attention to one thing. You both got work for a piece that was more information based/visual exploration. It's good, solid professional work from an actual client that communicates with your style and the portfolio you've already built.
I guess the only thing I would say is that industrial building on the top right doesn't really feel like it belongs in the same world as the rest of the buildings - everything is so 19th century quaint victorian style - but that might have been a direction you received from the client, and I really only noticed it after staring at the image for 5 minutes trying to find something constructive to tell you :-p.
Love it - brings me back to my childhood with Neopets.