Things to improve though;
Kind of unbalanced thats about all I can see.(E.G the bottom left barely any iron stone is further away [I think] xD) also the bottom players have to share a small amount of stone. of corse it always makes a good challenge with your AI lords at an advantage!
Others will probably say to make it not look as plain but I couldent care less. But its another thing to improve ;).
Of corse if you wanted a 5 you would need to have great map features.
Anyway the idea of the map is great I like it.