Sakrete/mortar bag retaining wall.

We moved to a house on the Brazos outside of Granbury, Texas last October. Our yard is about 400' long and about 30' behind the house it slopes down about 20' over the next 40', levels out to a gentle slope for around 150' and then falls about 15' to the river. We need to do something with the first slope to get it more manageable and are considering terracing it. We've talked to a couple or contractors who suggested that we use bags of sakrete stacked about 4' high every 12' or so. Has anyone used this method? Have you been happy with it? Any other suggestions that wouldn't put is in the poor house?

Thanks,
Linda