David Guretzki of Briercrest College and Seminary, and who supplied an after-dinner talk at the 2007 Barth Conference here in Princeton, has written (and made available on his blog) something of an introduction to Barth's Church Dogmatics for those who are approaching it for the first time. Having glanced over it, I recommend it to anyone who wants to get started with Barth as it highlights and culls from the secondary sources some important aspects of Barth's thought and what he is up to in the CD.
You can download the .pdf at David's blog. I have also updated my own So, You Want To Read Karl Barth? post with a link to this resource.