First off, I love the color scheme you used here. Your shading accurately depicts the bright light source on the horses (especially on the stallion). The only thing I can of that would make this piece even better would be to add some sand piled around some of the horses' hoves to give a better impression of them being "grounded" on the beach. And possibly adding a couple clouds in the sky to sort of break up that sharp horizon. Over all, your technique is very effective and you've balanced the picture nicely and showed a good sense of equine anatomy. Keep it up!