@Emre: You should turn down the shininess/ specular on some objects IMO, esp. on the stones near the water.
Additionally, those stones lack some sort of transition or blending into the sand. You could blend for example into a sand texture based on the stone's y-normal, preferably not with a direct blend (that looks like an alpha blend) but with some sort of irregular dirt mask as a multiplicator for the blend value.
Have a look at the following references I took some time ago: