There was an influence on the other Kagyu traditions. One of the Shamar Rinpoches wrote a commentary on it. These days it seems little known outside the Drikung Kagyu. I believe that Chetsang Rinpoche revived the study of it, prior to that it was not much studied in recent times.
The Gong Chik is a collection of sayings by the founder of the Drikung Kagyu, Jigten Sumgon. Some of the sayings go against commonly held Buddhist teachings, such as pramana (buddhist epistemology) teaches the ultimate truth. (Quoted from memory, not an exact quote.)
Imagine a man who stands before a mirror; a stone strikes it, and it falls to ruin all in an instant. And the man learns that he is himself, and not the mirrored man he had believed himself to be.
-- Gene Wolfe