It strikes me as a nice idea, and very similar to WikiText.

When I’m writing a Wiki article I need to learn a new formatting system (wikiText) which appears to be very similar to Markdown.

Personally I like the idea and, as you say, the idea is that it makes it simple to write on any device/editor. I do find it more time consuming when doing anything overly-complicated (example, a table).

For basic formatting — bold, indent, etc — it’s nice and fast

I wonder if this is where Google got the idea for Google+ posts? When you post you can use * _ or – to format text