Nice, clean and minimalist, but not exactly a drop-in replacement of WP Audio Player as advertised. In particular:
1. WP Audio Player allows setting custom media location (even outside the current site) and Haiku doesn't, leading to incompatibility.
2. WP Audio Player has a shortcode format with a pipe (|) for titles, like so [audio:file.mp3|titles=Extract 2.1]. That format is not recognised by Haiku, leading to incompatibility.
Since the Haiku player isn't that easy as a replacement I find myself exploring other plugins. A shame, because I love the minimalism.