I really like it. It takes a bit of getting used to though. If it were me I'd try to make everything look a little more smooth and shiny and a bit less rough. But this style works too, to be honest. Especially the white of the waves at the shore is interesting, though I think you should make the shallow water look less chunky, for a nice transition.
Also, perhaps, to add to the comment above me, you could make some more sand tiles (a couple with less detail) for variation, and to match the rest of the image more