Transition

My latest question is one I've been struggling with and would very much appreciate your opinion. This picture for example, I had the chance to snap from dawn to dusk but chose a time just before the last trace of daylight was to disappear. I know it might have been more dramatic other times, but this type of scene is one many of us have experienced and one I wanted to capture, and this pretty much represents what the eye sees.

So my question is, when is a picture too dark? if this doesn't appeal to you, does it also mean you wouldn't have enjoyed being at the scene at this time? And if you do like this, what details might you want to see that isn't represented here? Please, don't be shy to express your opinion. A large view might help cover more of your field of vision against a white background.