Used pandoc for a couple presentations recently and while it's clear the experience will be wonderful eventually, it's still a bit buggy. There is no widescreen template included with Pandoc and attempts to use other templates caused me to encounter https://github.com/jgm/pandoc/issues/5402 . The resulting .pptx files won't open in Keynote, either, but luckily they did open in Google Slides, which then let me download a visually-identical .pptx that opens everywhere. Point is, slide support in Pandoc is still somewhat new and people should not go in expecting a trouble-free experience at this point.

I love pandoc, and I would love it even more if it had full support for LaTeX math. Unfortunately, the math support is very primitive (meaning, I cannot copy-paste maths from my LaTeX paper and expect it to work and look correct once converted to html, even with the mathjax option). I spend a weekend trying to hack the haskell code to correct a few problems, but it got to nothing.

I use pandoc to output revealjs presentations when I want to present web things (with links, videos or gifs). And it is good as I have some teaching content that I use in webpages, in presentation and for print.

Presentation notes kind of work, but I don't like them (in general, not just for revealjs)?