Jim,
Wild Horse is really good for many of the same reasons all really good course are really good.
The course features an excellent variety of interesting holes and green complexes; there's plenty of interesting contour throughout the course (complimented by firm, sandy ground); beautiful bunkers, grasses and vegetation provide the property with gorgeous texture, and help with melding golf holes into their native surroundings. As you can see, the course is very, very nature in appearance.
Moreover, Wild Horse doesn't beat you as much as Sand Hills can. Wild Horse is constructed on a more subtle property, on a much smaller scale than Sand Hills. In turn, it's not as difficult. This is not to say Wild Horse is a push-over. It isn't... especially when the wind's up.