It completely fixes a huge number of the gripes in the JupyterCon talk I don't like notebooks by Joel Grus.

The primary complaint there is that notebooks have a disconnect between the state of the program and the display of the cells. By using a completely reactive mode the state is no longer hidden. It's more akin to a spreadsheet than a notebook. A number of other complaints are completely circumvented by using a file format that's simply a pure Julia file with clever comments.

Video: https://www.youtube.com/watch?v=7jiPeIFXb6U

Slides: https://docs.google.com/presentation/d/1n2RlMdmv1p25Xy5thJUh...

Previous discussion: https://news.ycombinator.com/item?id=17856700