Simple but powerful. The only caveats:
- This extension is much too quick to convert symbols to markup -- e.g. if you are trying to jot down math notes (like "-2 * 3 = 6 * -1") the extension WILL italicize the "3 = 6" instead of leaving the asterisks untouched. Which is an "always on" behavior, you don't get any means to disable it.
- The extension is no longer actively maintained (so issues like the above are NOT going to be fixed ... ever).

I'd love to find a note-taking extension to serve as an updated version of this one, but until that day comes, this is still one of the best (despite its flaws).