I absolutely adore how you used brown to create grass that appears to be green when surrounded by the unsaturated reds. I had to take this into photoshop to really get an idea of how cleverly you use colors. The contrast between the foreground and the background is lovely as well. blah blah mindless praise blah
Have you created somekind of a custom brush for the "grainy" feel in the picture? Especially distant landmass and the front rocks. I like that effect alot, gives it a lively feel!
I'm not sure how big the gate should be compared to people, but for some reason it appears rather tiny. Could it be because the rock formations at the front just fade into the gate? Meaning, there's no visible border where the rocks should end, as I'm presuming there's some road going behind them.
Otherwise, I really envy you for the feeling of space you are able to create, gotta look into it and see how it's done.