After 45 minutes, my index fingers are absolutely warn out from using a trackpad. I really wish he would have made it navigable by more than just click & drag. I do wish this was more thorough, though.
To me that's why its so magical. Its actually expensive in time and effort to navigate, so you feel like you're investing something in order to explore. This also means that its difficult to see every part of the image, so you're left with a sense of frontiers yet unexplored when you navigate away from the page. The zooming versions are cool but, to me, actually take away from what Randall is trying to achieve here.
I thought that it was the "click" part of the original navigation that really frustrated me, rather than only seeing a little bit at a time. I gave up on the original in a few minutes because my hands/wrists were aching after using a touchpad and then a mouse
I used the zoom versions after the fact primarily so I could swipe to look at the original 1:1 more comfortably, and then only later to follow up on what I thought (correctly) was just a bunch of blank space. Clicking to drag specifically really dampened my enthusiasm for going off in random directions to investigate the whole thing.
I think it still works with zooming because the scale is so extreme that it leaves you wondering whether a tiny smudge is worth zooming in on. And once you zoom in far enough to read the text, the surrounding objects look as big as they're meant to be.