While Korea (well at least just about all you can see of Korea, which is most) has a good shape, just about everything else is completely out of proportion. The Bo Hai and Korea bay do not look too much like the real thing, rather, this looks like you cut out the Bo Hai completely and used just the Korea Bay. China isn't awful, it just doesn't look correct compared to a real due to the fact you cut out Bo Hai.
The map isn't unusable, and should probably best serve a strictly Korean defensive scenario. Problem is, the map is a big one, so there is really little point to staying in one area on such a huge map.
This is about average. I'd figure there are people who could use this map for a Choson v Shang scenario, and I'd also figure there are people who would rather just make one that's a bit smaller and more accurate.