I viewed it in Chrome on Linux and it took me quite a while to figure out that you advance by clicking the solid black bars on the side of the slides (which don't even show if your browser window is too narrow). More of a UX issue than a technical one, I guess.

Same here. Arrow buttons of some sort would help.

I hadn't even noticed how I was going through the presentation until you mentioned it.

The problem in Opera is your feature test in slide-deck.js line 762. At the time this part of the code executes, the DOM is not ready yet, so document.body is just null and the whole thing fails.

It does however work perfectly after executing window.slidedeck = new SlideDeck(); manually.

I used chrome and almost just exited the page until I accidentially clicked on the black part next to the slide. That's not a browser issue.