Lacking drama in the light - just overall too bright a shot for me. Levels, or curves work to bring the contrast out in the scene more strongly would have made it so much more appealling - and possibly helped with that odd greenish cast in the sky.
Doesn't look so much like a rodeo rider as a scene from a parade... that horse has three hoofs on terra firma. A nice travel photo though. Sure raises my interest in Mesquite...