The model looks fantastic. I'm not as sold on the shaders mostly because getting plants to look right with the translucency is always tough. What breaks the realism for me is the leafy areas and the trunk of the tree. I'm not sure if it's that the ambient occlusion feels off or if it's just the texture, but something feels a little plastic in there somewhere. That's the only thing I would say could be better though, love the model.