I tried pre5 and noticed two problems that nobody seems to have mentioned yet.

I can add a folder of songs for uploading just fine. But I am unable to add any single tune for upload.

The other problem involved a failed sync. Everything went a bit funny on me, views were not refreshing and such. So I 'reconnected' to the player and everything came up just fine. The batch of songs that was being uploaded never made it to the player (not even found with refs == 0) but I couldn't re-add them until I disabled duplicate detection.