I don't know much about Barth (Gasp! How then can I be taken seriously as a theological thinker???), but I thought this was an interesting piece by William Evans on the subject. His conclusion is particularly provocative:
I am also struck by the parallel to Friedrich Schleiermacher--a comment that will probably surprise those who hold to the conventional view of Barth as an implacable opponent of the "father of liberal theology." In the mid-nineteenth-century context Schleiermacher was trumpeted as a bridge from the barren rationalism of Kant to orthodoxy. The church historian Philip Schaff, for example, argued in this fashion (see his Germany: Its Universities, Theology, and Religion [Philadelphia: Lindsay and Blakiston, 1857], 320). But bridges can be crossed in both directions, and while initially the preponderance of traffic over die Schleiermacherbrücke was toward more conservative forms of theology, the long-term story has been quite the opposite. I sense that the same is and will continue to be true of Barth.