For some time now I have used asciidoc to write all my notes. I even use asciidoc to write this blog.
My main use case was that I wanted to be able to send a proper report of what I was doing especially when investing a problem. I took this habit while working with an architect who sent a note to the project manager at the end of each day when working on a problem. This note contained all his paths of research. Such note was really helpful when you had to work on the problem after him.
The advantages I find in using asciidoc are :
Clear syntax (quick syntax)
Can generate proper output in many formats
Can easily be reused in a project documentation
Only need a simple text editor
I had to find some disadvantages :
Need to have some tools installed to use all the features
Have to learn the syntax to properly modify a note
For me no better argument than an example to really show you why I use asciidoc :
To properly and easily access my notes I push them in a git repository but I have heard about using asciidoc with Evenote (asciidoc vim Evernote).