IDE-style notebooks are a godsend for projects over a certain size threshold. They encourage people who aren't typically used to "programming in the large" to start folding unwieldy chunks of code into files, which in turn encourages them to experiment with the abstractions and structure that software engineers use to handle scale. Notebooks got this wrong, Jupyterlab (and RStudio) get it right, and it's a huge step forward!
That said, Jupyterlab has growing pains. Things like ipywidgets that used to Just Work now Just Don't -- if you want to use widgets as seen in the screenshots, you have to separately install npm, learn to grok the jupyterlab extension manager, and surf the version compatibility matrix between the backend ipywidgets you have installed and the frontend ipywidgets you have installed. Sigh. I'm sure it'll iron out in time, but every time I see the screenshot with widgets in it I have to clear my throat.
That said, Jupyterlab has growing pains. Things like ipywidgets that used to Just Work now Just Don't -- if you want to use widgets as seen in the screenshots, you have to separately install npm, learn to grok the jupyterlab extension manager, and surf the version compatibility matrix between the backend ipywidgets you have installed and the frontend ipywidgets you have installed. Sigh. I'm sure it'll iron out in time, but every time I see the screenshot with widgets in it I have to clear my throat.