A calm day missing some elements
overall the light and color looks great no question about that. The texture one the ground is very finely detailed as well. There just needs to be more then just a tree, an ocean, and the sun.
I know this is not a new work based on your authors comments, but when it comes to landscape pieces, its best to remember the concept of: foreground, midground, and background. a subtle mountain range, a boat/ship, or a land mass in the background would probably help.