The nice thing about the original Markdown (modulo bugs) is that things are written the way one would write plaintext documents which are supposed to be easily read in a text editor. So you don’t write bullet lists like this:
- Bullet 1 - Bullet 2 - Bullet 3
And hope that some post-processing will add linebreaks for you. You write it like this:
- Bullet 1
- Bullet 2
- Bullet 3
Similarily there have been many tools that let you add so-called ASCII-art diagrams to Markdown documents.
The spirit behind the kind of thing in the OP, on the other hand, is that one should get nicely formatted HTML from Markdown for the purpose of online consumption. Which is a very different goal.
So if I were to judge the syntax itself (since that is what matters most to the original spirit of Markdown.pl) I would say that it seems pretty decent. Not as “declarative” (!) as ASCII-art, but most probably much easier to edit.