It's looking good, but I Karro is right about the mountains, they look like they're floating over the land. Have a look at the post in my sig about mountain boundries which may (or may not!) be of help. It also seems to me that you've got an effect where the land is standing proud of the sea, probably because of the perspective cloud effect and the fact that it's apparent that the cloud effect continues behind the landmass and comes out of the other side...another sea texture maybe?

Great work so far though!