Wow! Things are really looking good! I made a list of suggestions that you could possibly consider.
- The Island has good shape and I really like the river systems, but I suggest you make some parts of the river deeper.
- I am guessing you are working on adding grass and other assorted foliage near buildings. In some towns there was no grass.
- Keep up the great work and adding really cool landmarks (Bases, airfields, docks, etc.).
- Also, random rock!
All in all, I think what you have here is very good!