Barth is a rather creative thinker who brings you into conversations you would never be in if you stuck to engaging with those who are theologically familiar to you. In that way, he makes you consider and reckon with issues through angles that you would not have otherwise, which grows you as a thinker. I think there can be a healthy, critical appreciation for his contribution to the theological enterprise, but the extent to which some are "enamored" by him is too far in my estimation. Relating this to the OP, it seems strange to call one a "great" or "favorite theologian" who was so habitually unfaithful to his wife.