Keynote is completely underrated, likely because people assume it's just a Powerpoint clone, but it's more like a highly templated motion graphics app with a UI that steers people into using it as Powerpoint replacement.

So not only is it a far quicker way to make a PPT than using Powerpoint. I also see it used for making presentation videos, interactive PDFs and even animated GIFs/HTML5 animations.

The number of motion graphics marketing videos I see which are actually just Keynote files exported to video is impressive.