The overall look is good, the fog gives it a nice island feeling.
As for the trees, shadows are really recommended to spice up the realism like Frank indicated. You've got the choise between z-buffer shadows and stencil buffer shadows but you should make a calculated thought about using which kind of shadow. Z-buffer shadows are faster but they don't countour around objects, stencil shadows are slower but they look better due to the faqt that they contour around level geometry, models, sprites,... I would recommend using z-buffer shadows for the scene itself and stencil shadows for the main player. The grass texture, I wouldn't add anykind of bump mapping ( tangent space bump mapping / object space bump mapping) because they both have their cons and pros. Tangent space bump mapping is slower because you use more instructions to transform the light and view vectors to texture space. Object space bump mapping is faster but it behaves badly with mip mapping which is a requested use when texturing a large surface. I would just use a multitexture terrain shader. About the bloom shader, I can only confirm what Julz said about it. A water shader is always abit tricky to get right, especially at the shore but I'll judge that when I've seen a clear shot of it in one of your next updates. About the vegetation, SEED-IT is a potential solution for sure but it will cost you a small amount of cash But the amount of money you spent on it is nothing compared in comparasion with the great results you will get in return ^^ !!

For the rest I can tell you that you're on the right track about the level design, a nice progres vartan Waiting for updates

Cheers

Frazzle