You certainly picked an excellent vantage point for this shot. Those clouds are pretty awesome. I'm sure it was intended, but I think the overall softness in the processing takes something away.
The elements of the composition are strong but there are a few areas that need improvement to push this up into an above average category. First off is that (on my screen at least for I know everyone's screen is different) the shape of the muzzle of the mama horse gets lost in the neck portion of the baby horse. The tones of both horses are so close that they just blend into one another. Taking a couple of steps to the right or left or even waiting for them to move a bit more apart would have helped 'separate' them to show two separate 'individuals'. Now the sepia tones really add to the composition for it invokes imagery of an era gone by & the ol' west. But as much as that is a strength it also, unfortunately, is a weakness. There is soo much cloud cover that with minimizing the color palate down to a few hues it does not allow for much dynamic tonal range plus it just makes that sky busier thus calling away some attention from your main subject - that of the lone horses waiting on the hillside. Waiting for less cloud cover would have been the best solution BUT then you most likely would not capture those two lovely lone horses on the hillside which is the main focus of your shot. Not having seen the color version mayhap the color shot would have been a stronger composition that shows greater dynamic range in color hues.
Looks like somebody went shooting together for this. :-) I like this post-processing of the sky better in this. Having a cutesy foal/colt in the comp will certainly boost the score. Title works well also. Good luck.