I'm the author, and I'm happy to answer any questions. The book should be in print by (hopefully) the end of this year, or definitely by Jan 2017. The content will not change significantly, but there is will be minor fixes and a lot of proof reading.
Is there (or are there plans for) a version of this in Jupyter notebooks?
I came from Python using iPython. I missed them for the first few weeks, but now I can't switch from RStudio. It really is just such a great tool for data science.