Probably not base case but a quick test to replace my audio player (currently using Plyr) turned up the following gaps for me, at least with the out-of-the-box code.

1. No playback rates under 1

2. No volume rocker on mobile

3. Would appreciate having seek buttons on mobile too

4. No (easily apparent) way to add an accent color, stuck with boring monochrome

5. Docs lacked clear example/demo/playground so I wasn't sure what it would look like until implemented