This looks already nice ! Your grass texture looks good too and enhances the sensation of speed.
Designing 3d environments is not that easy (I am stuck to 2D so far). When you say "platforming", why do you mean in 3D ? I have myself a project of 3D platformer but which much more simplistic objets.
Just one think looks a bit strange to me : it seems all shadows are reddish, is it wanted ?