I know I'm a little late to this thread, but here's my .02.

The one thing that really struck me was the odd colors of the trees in the shadow areas.  One thing that I always do is tweak the texture's Diffuse and Ambient in the Effects tab of the material screen.  The default ambient, to me, is too high.  I always take that from the default of 40 to about 33-36.

I also usually take the shadow density down to about 75%.  Always seems to work well for me.

Other than that, it's a nice image.  I kinda' like it!