To be honest I kind of like it. I was confused at first as well but this does allow you to more quickly go between sections of a powerpoint which just isn't possible with the traditional "you can only swipe left or right" presentation.

Not only that but it also makes it much easier get an overview about what things are discussed in the presentation.

I'm shocked that the top two HN comments as of writing are bikeshedding the submission's web design.

A presentation is designed to be mainly useful for the presenter. In an actual presentation I could see it useful to navigate between main chapters when I get questions at the end. Now that it is shared and some people have minor problems navigating it at first is much lower priority. Maybe the shared slides could be linearized.

To jump on the bandwagon here, I recently set up a gopher site for a friend running for local office (sort of as a geeky in-joke). I came away from the experience actually wanting more gopher. Yes, the web can be a platform for things that should be simple documents, but gopher all but guarantees a uniform UI and nothing but content.

I didn't bother to figure out the multi-dimensional navigation of these slides. Paraphrasing Tufte, Richard Feynman managed to write about much of physics without resorting to more than two levels of headings. I'm similarly unconvinced that multi-dimensional, nested documents are really that helpful here.

Oh! You go down until you run out of slides then you go right.

similarly at first it confused me, but now I understand it is like a table of contents which is useful and easy to use.