Here are some quick impressions of my initial use of the AP80.
Database Mode
Seems to work much as previous non-touch Hiby OS versions. The Genre menu remains a useless wasteland, since it has no hierarchy beyond Genre, then ALL songs in that genre. Artist still seems to be the Song Artist field, and not the Album Artist field. This makes compilation albums impossible to play without delving into the folder view. The database updates about as fast as the AP60II, maybe slightly faster. I'll have to do a side-by-side test of the same file load to be sure, but the AP60II takes about 5 minutes to parse my usual set of tunes (about 7000 mixed FLAC and MP3), and the AP80 takes not much less time. Definitely faster than a Clip Zip, but you'll definitely want to update the database only when you don't need the player any time soon. On the plus side, unlike the AP60II, you can turn off automatic database updates (AP60II claims to do this, but it updates anyway when you unplug it).
Playlists
Just as with every other Hiby-based player, external playlists are not easily integrated into the database mode. Since this is how all MP3 players worked until the bottom dropped out of the market in recent years, this is annoying. The Hiby R3 introduced the ability to "load playlist" from the /playlist_data directory, although you first had to create one playlist on the player before the OS would recognize the directory (can't create it yourself). I don't have an R3, but based on the discussions in its thread, it seems that I should be able to put standard M3U playlists in that directory, hit "load playlist" and have them actually work in the database mode. So I tried that this evening. All the playlists showed up, after a seemingly endless processing time. None of the playlists have any songs in them.
If I go to the folder view and navigate to those M3U playlists, they all work fine.
Does anyone have any insights on this yet? I'll poke at it some more this weekend, but it's annoying how little love external playlists ever get from the Chinese DAP developers.
Replaygain
Replay gain is finally a setting in Hiby OS. It's hiding in the playback settings menu, which is found inside the Player function, and not in the root menu as in older non-touch Hiby versions. I haven't tried any songs that I know have wildly varying replaygain values, so I'm not sure how well it works, but it has three settings: off, album, and song. This matches the standard ReplayGain settings from the Sansa line of last decade. Yay, finally getting features that were standard in 2005!
Podcast/Audiobook Support
Still nothing. No bookmarking, automatic or manual. No speed/pitch control. No recognition that Podcast or Audiobook is anything other than a genre of music.