Christendom has been vexed by the grace vs. works debate for thousands of years. Certainly it is the main issue evangelical Christianity has with Mormonism, and the issue that the reformers had with catholicism. More recently, "liberal" mormons have articulated issues with the traditional mormon attitude toward it.
I think, in this talk, President Uchtdorf articulated the relationship between grace and works in profound ways and with a clarity I have not encountered before. It is comforting, vivid, compassionate, and feels right: