I just registered to this site and this is my first post.
Firs off, let me say I am glad someone else seems to be using CC3, too. I have been using it for some time now and have created maps for my campaign set in Norwold of the D&D Gazzetteer series. I might be brave enough to post some here. I started with CC2 over 2 years ago and moved on to CC3 when it was released. I bought it at the gaming fair in Essen which was a nice deal since you could talk to one of its creators there. I also strongly recommend the tutorials from Joe Sweeny (not sure about spelling) on YouTube.
Concerning your map, I can only congratulate you on your use of the Sheet and Effects. The glow on the shore and the Map names are excellent. I'd like to give you some advice on the changes I'd do.
Was it supposed to have no settlements? Because of the fact that most settlements are built new water bodies those on this map will probably be near the shore. Otherwise I'd recommend creating some rivers which would lighten up the overall picture. How about some vegetation? Even if all the land around the mountains was plain a couple of single or 2-3 tress distributed here and there make it seem a little more "natural". The mountains to the upper north and the utmost south look great because you didn't line them up in a straight way like you did in the middle part. I'd recommend putting the mountains in the middle slightly off each other a bit. Might not look good though. I will try to post one or 2 of the 12 maps I did for my campaign and you can tell me, too, what you think of them. Maybe we can be inspired by each others maps and thus profit both from it.