You forgot some tiles on the right side of the level follow the water cliff.
Shallow Water needs detailing there are two types of water deatil for this. Maybe giving it a more irregular pattern too.
The grass to water looks bad you're better off turning it into a beach with the beach tiles.
Be sure to use all the sand tiles not just one type of sand. Plus the rocks. There are 3 types of sand tiles and two rock sand tiles. Be sure to use a mixture of all 5 but dont go over board on the rocks.