The IDL 8.5 feature that I am most excited about is the Jupyter notebook kernel for IDL. For a certain type of analysis, the notebook is a great tool for both recording an interactive session as well as presenting it to others. From the Jupyter documentation:

The Jupyter Notebook is a web application for interactive data science and scientific computing. It allows users to author documents that combine live-code with narrative text, equations, images, video and visualizations. These documents encode a complete and reproducible record of a computation that can be shared with others on GitHub, Dropbox and the Jupyter Notebook Viewer.

The IDL kernel provided in IDL 8.5 works well. The only issue I had with the notebook was that only the first direct graphics plot was displayed. The workaround was simple, though a bit tedious — I just needed a WINDOW command before each plot. I had no issue with function graphics plots, widgets, or non-graphical commands in my first explorations.

I’m still uncertain of the exact use cases for which the notebook will be valuable, but I intend to spend some time trying to find them. As a simple example, here is a notebook (and HTML representation) of the first section of my book, Modern IDL.