It's broken. It can stream via spotify, but if I try to play vbr AACs, the sound just cuts off after a minute and sometimes comes back, sometimes it doesn't. The VU meter freezes, too. Navigation is broken, the back button sometimes works, sometimes it doesn't.
EDIT:
What on earth. I reformatted the unit once again, it lost all battery, charged it and scanned my library. It now works flawlessly. Spotify works pretty good, too.
What I found.
1) The leatherette protector doesn't let you select the menu or back buttons correctly. It fits too closely to the software buttons. So, there's problem #1.
2) I had disabled the Browser and email apps, thinking I could speed up the unit. When I reset the whole thing (again), I left everything enabled.
I don't know if this helped, but I have been listening to the unit for two hours without an issue.
I'm slowly warming up to the sound. Speed is pretty much OK, it's completely usable now, and appropiate to a DAP, I guess.
I'll use it all day today and see what happens.