Could it be you only have the free version of TG2?
If not, I suggest you render with much more AA, higher quality and higher resolution. Your scene elements are becoming better and better, but your render quality now lags behind.
Lastly, another suggestion. Renders look much better if you take a clear decision on what you want to optimze the exposure for: terrain or sky. Usually, when people try to bring out both equally, each element becomes rather mediocre (in their lighting), resulting in the image looking a little bit flat. In this render, I would try to expose for the vegetation more.
Cheers,
Frank