I like the idea behind this and other projects like it, but I have one main issue with it/them:
It isn't trivial to share presentations, which is something that most people will want to do. Sadly the fact that you can build a presentation in HTML (and that people can look at it online) doesn't outweigh sharing a PDF. Don't get me wrong, I'm all for lighter more flexible solutions (which html is), but the market as a whole generally isn't.
I fucking hate PDF on the browser. It's very slow to download, take up huge resources, hard/not lenient in re-sizing and is the worst choice for presentations.
This is a lot better choice, but each scenario has different needs. PDF is good for books, and long documents.
It isn't trivial to share presentations, which is something that most people will want to do. Sadly the fact that you can build a presentation in HTML (and that people can look at it online) doesn't outweigh sharing a PDF. Don't get me wrong, I'm all for lighter more flexible solutions (which html is), but the market as a whole generally isn't.