I definitely plan on checking this out. Another nice programmer's notebook I've been using for awhile is Marxico https://marxi.co/. It's integrated with Evernote, but I think you can use it standalone.

It supports Markdown, code snippets (in markdown ```), latex and sequence/flowchart diagrams.

To me it feels a little more natural to write a markdown document rather then thinking about each block of text as "cells".