In reluctant accord with the annoying trendiness of Barth in evangelicalism (or is it just here at Wheaton?), I'm reading through the engagement with Barth from an evangelical perspective of mostly British scholars and edited by a recent grad of Aberdeen (under Francis Watson) and a theology prof at Oak Hill in London. The essays have been very helpful. Mike Ovey's in particular I appreciated (on the Trinity), as I'm in a doctoral seminar at the moment on the Trinity and Barth has been our most recent theologian of discussion.
Anyhow, Andrew McGowan contributed on Barth and (what else?) covenant theology, and something he said in his conclusion was very helpful and put words to an uneasiness I've been feeling myself in my forays into Barth this year.
Barth's natural instinct to give priority to Christ over Adam is understandable. Adam was a 'type' of the one who was to come and therefore in some fundamental sense we must view Adam in the light of Christ. Nevertheless, Christ is also the second (or last) Adam. In his desire to be Christocentric, Barth has failed to take the biblical account of history seriously. Indeed, it can perhaps be argued that one of the overall weaknesses of Barth's theology is a lack of proper 'grounding' in the redemptive-historical context set out for us in Scripture.
--A. T. B. McGowan, "Karl Barth and Covenant Theology," in Engaging with Barth: Contemporary Evangelical Critiques (London: T&T Clark, 2008), 134