In general I like the coast and the rivers. The islands look natural (to me). I think thats a good start for a map
I can't associate the land with the distance of 1000 miles. It looks like something smaller.
That may be the effect of the giant (more than 1 inch = 50 miles high) symbols of the mountains in the north of your map. If you are going to make the mountains that high, you should change the scale. Or you can make them a bit smaller.
On the other hand I'm not sure what style of the map you are going to achieve. So may be my comment (about the scale) is just a result of a misunderstanding.