I think you got unlucky with the weather on this occasion - the sky is totally flat and it looks like mist hasn't helped the far trees, while not being thick enough to add interest. It's often said that "green sucks" - there's not a lot of separation between the near green and the far green to make the chasm immediately obvious. For a decent landscape with lots of green, it's good to have a strong colour to contrast, eg blue sky. It's difficult to say what you could have done about any of the above though, other than ask for different weather, and interesting blue sky with clouds etc. I think you could have made the castle more interesting, perhaps by taking an angle more to the side, showing the gaping windows etc - at the moment its not very clear it's a castle. A higher angle might have revealed a bit of the drop into the chasm, but without being there, obviously I can't say with any confidence. If there is any valuable advice though, it might be the "conventional wisdom" in an overcast situation like this, which is to go after details where there is interesting texture. Perhaps a plant growing from that interesting wall, crumbling mortar etc. Overcast light is supposed to be good to enhance textures. Also perhaps using the sky for silhoutte might have been possible - say the sky through a castle porthole, barred window or some such.
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