I'll add that it's a great way to teach python to students. Notebooks can be shared and students basically retain all their legwork as they learn. It's very helpful for visually seeing code work if you are new.

Although it has and allow the creation of extensions which provide a lot of usefull features. In this version, the nbextensions are introduced as python packages, so that they're even easier to use/install.

The best thing with Jupyter Notebooks, is that one can write text with markdown, show formulas with LaTex (using MathJax), show code inputs and outputs in REPL-style, all together with possible Bash use, other languages' snippets, and nice cell %magics.

So it is possible to run both R and Python commands in the same notebook?