The scene looks really good my only crit would be it looks a little bland and blocky.
On your edges (on pretty much everything) add some detailing a little goes a long way to make the scene feel more believable. This is the same on your shadows a tree wouldnt normally have that harsh line on the shadows.
Final point - have you used any bump maps, if you have they are far to subtle so that i cant even tell.
Seems like a great start but i think you could get more out of it.