Minecraft/Realistic landscape

Hi !

Today I created this picture with a friend:

He created the characters in a different software (Mineimators) and I created the background:

I added the characters with compositing. For the mountain, I’m using the texture from this model: http://www.blendswap.com/blends/view/81252

The final image will be used on a website, but will be this size:

There will probably be a text on it, but I’m not sure.

Well, what do you think of it? What could I improve on the HD version?
Any tips about compositing?

Thanks !