Works well but help section lacking...

It does not work w songs in MPEG (MP3) format that are synced through Apple Cloud if you have their music service. Songs you have bought through iTunes in AAC format work fine. So if you have music from CDs that you have transferred to iTunes, the app wont be able to read the files because Apple encrypts them when they go from the cloud to your iPhone. You can work around this by transferring MP3 files directly to your iPhone like you did in the past w your phone cable and the USB port on your computer.

jo kickass about Amazing Slow Downer, v5.5.4