I haven't finished the walkthrough yet (I defeated the last green castle, and it lost), and there's still the yellow one ahead, but for now, I'm happy with the map.
There are a couple of minor issues, but it's up to you whether to change them; personally, I would like to change these things, but you can decide for yourselves.
1) The stone mine is very far from the city, and you have to fight your way there; the lumber mill is also far away, but these are the most necessary resources at the beginning. At the same time, the sulfur and gold mines are close to the city; I would swap their locations (the lumber mill with sulfur, stone with gold).

2) This is a bit visually jarring.

And I would like to thank you for including a mentor; I like that in single-player maps =)